FIG. IV. Various Lobosa. 1, 2, 3. Dactylosphæra (Amaba) polypodia, M. Schultze, in three successive stages of division; the changes indicated occupied fifteen minutes. a, nucleus; b, contractile vacuole (copied from F. E. Schultze, in Archivf. Mikrosk. Anat.). 4. Amoeba princeps, Ehr. (after Auerbach). a, nucleus; b, c, vacuoles (one or more contractile; the shaded granules are food-particles). 5. Pelomyxa palustris, Greeff (after Greeff), an example with comparatively few food-particles (natural size th inch in length). 6. Portion of a Pelomyxa more highly magnified. a, clear superficial zone of protoplasm (so-called "exoplasm"); b, vacuoles, extremely numerous; c, lobose pseudopodium; d, a similar pseudopodium; e, nuclei; f, "refractive bodies" (reproductive?); scattered about in the protoplasm are seen numerous cylindrical crystals. Arcella vulgaris, Ehr. a, shell; b, protoplasm within the shell; c, extended protoplasm in the form of lobose pseudopodia; d, nuclei; e, contractile vacuole; the dark bodies unlettered are gas vacuoles. 8. Cochliopodium pellucidum, Hert. and Less. a, nucleus surrounded by a hyaline halo sometimes mistaken for the nucleus. whilst the latter is termed

nucleolus.

7.

few cases, but not fusions of many individuals so as to form plasmodia; nevertheless the size attained by the naked protoplasm by pure growth is in some cases considerable, forming masses readily visible by the naked eye (Pelomyxa). The presence of more than

one nucleus is a frequent character. A contractile vacuole may or may not be present. The formation of sporocysts and of chlamydospores (coated spores) has not been observed in any species, but naked spores (flagellulæ or amoebula) have been with more or less certainty observed as the product of the breaking up of some species (Amoeba? Pelomyxa). The cyst phase is not unusual, but the cyst appears usually to be a hypnocyst and not a sporocyst. In the best observed case of spore-production (Pelomyxa) the spores were apparently produced without the formation of a cyst. Reproduction is undoubtedly most freely effected by simple fission (Amoeba) and by a modified kind of bud-fission (Arcella). Freshwater and marine. Two orders of the Lobosa are distinguished in accordance with the presence or absence of a shell.

ORDER 1. NUDA.

Characters.-Lobosa devoid of a shell.

Genera.-Amaba, Auct. (Fig. IV. 4); Ouramaba, Leidy (with a villous tuft at one end, Wallich's A. villosa); Corycia, Duj. (low, ridge-like pseudopodia); Lithamaba, Lankester (Fig. V.); Dinamaba, Leidy (92) (covered with short stiff processes); Hyalodiscus, H. and L.; Plakopus, F. E. Schultze; Dactylosphæra, H. and L. (Fig. IV. 1, 2, 3); Pelomyxa, Greeff (Fig. IV. 5, 6); Amphizonella, Greeff (forms a gelatinous case which is broken through by the pseudopodia).

ORDER 2. TESTACEA.

Characters.-Lobosa which secrete a shell provided with an aperture from which the naked protoplasm can be protruded. The shell is either soft and membranous, or strengthened by the inclusion of sand-particles, or is hard and firm.

Genera.-Cochliopodium (Fig. IV. 8), H. and L.; Pyxidicula, Ehr.; Arcella, Ehr. (Fig. IV. 7); Hyaosphenia, Stein; Quadrula, F. E. Schultze (shell membraneous, areolated); Difflugia, Leclerc (shell with adventitious particles).

Further remarks on the Lobosa.-The Lobosa do not form a very numerous nor a very natural assemblage. Undoubtedly some of the forms which have been described as species of Ameba are amoeba forms of Mycetozoa; this appears to be most probably the case in parasitic and stercoricolous forms. But when these are removed, as also those Proteomyxa which have pseudopodia of varying character, at one time lobose and at another filamentous, we have left a certain small number of independent lobose Gymnomyxa which it is most convenient to associate in a separate group. We know very little of the production of spores (whether it actually obtains or not) or of developmental phases among these Lobosa. The common Amoeba are referable to the species A. princeps, A. lobosa, Dactylosphæra polypodia, Ouramaba villosa. Of none of these do we know certainly any reproductive phenomena excepting that of fission (see Fig. IV. 1, 2, 3). Various statements have been made pointing to a peculiar change in the nucleus and a production of spores having the form of minute Amoeba, arising from that body; but they cannot be considered as established. Whilst the observed cases of supposed reproductive phenomena are very few, it must be remembered that we have always to guard (as the history of the Ciliata has shown, see below) against the liability to mistake parasitic ambula and flagellule for the young forms of organisms in which they are merely parasitic. The remarkable Pelomyxa palustris of Greeff (32) was seen by him to set free (without forming a cyst) a number of amobule which he considers as probably its young. Mr Weldon of St John's College, Cambridge, has observed the same phenomenon in specimens of Pelomyxa which made their appearance in abundance in an aquarium in the Morphological Laboratory, Cambridge. It seems probable that the amoebule in this case are not parasites but spore-like young, and this is the best observed case of such reproduction as yet recorded in the group.

Arcella is remarkable for the production of bud-spores, which may be considered as a process intermediate between simple fission and the complete breaking up of the parent body into spores. As many as nine globular processes are simultaneously pinched off from the protoplasm extruded from the shell of the Arcella; the nuclei (present in the parent Arcella to the number of two or three) have. not been traced in connexion with this process. The buds then become nipped off, and acquire a shell and a contractile vacuole (33).

The presence of more than one nucleus is not unusual in Lobosa, and is not due to a fusion of two or more uninuclear individuals, but to a multiplication of the original nucleus. This has been observed in some Amoeba (A. princeps?) as well as Arcella. Pelomyxa (Fig. IV. 6) has a great number of nuclei like the Heliozoon, Actinosphærium (Fig. VIII.).

Pelomyxa is the most highly differentiated of the Lobosa. The highly vacuolated character of its protoplasm is exhibited in a less degree by Lithamoeba and resembles that of Heliozoa and Radiolaria. Besides the numerous nuclei there are scattered in the protoplasm strongly refringent bodies (Fig. IV. 6, f), the significance of which has not been ascertained. The superficial protoplasm is free from vacuoles, hyaline, and extremely mobile. Occasionally it is drawn

conc

FIG. V.-Lithamoeba discus, Lank. (after Lankester, 34). A, quiescent; B, throwing out pseudopodia. c.v., contractile vacuole, overlying which the vacuolated protoplasm is seen; conc, concretions insoluble in dilute HCl and dilute KHO, but soluble in strong HCI; n, nucleus.

muddy ponds (such as duck-ponds), creeping upon the bottom, and has a white appearance to the naked eye. Lithamoeba (Fig. V.) is distinguished by its large size, disk-like form, the disk-like shape of its pseudopodia, the presence of specific concretions, the vacuolation of its protoplasm, and the block-like form and peculiar tessellated appearance of its large nucleus, which has a very definite capsule. In Lithamoeba it is easy to recognize a distinct pellicle or temporary cuticle which is formed upon the surface of the protoplasm, and bursts when a pseudopodium is formed In fact it is the rupture of this pellicle which appears to be the proximate cause of the outflow of protoplasm as a pseudopodium. Probably a still more delicate pellicle always forms on the surface of naked protoplasm, and in the way just indicated determines by its rupture the form and the direction of the "flow" of protoplasm which is described as the "protrusion" of a pseudopodium.

The shells of Lobosa Testacea are not very complex. That of Arcella is remarkable for its hexagonal areolation, dark colour, and firm consistence; it consists of a substance resembling chitin. That of Difflugia has a delicate membranous basis, but includes foreign particles, so as to resemble the built-up case of a Caddis

worm.

Arcella is remarkable among all Protozoa for its power of secreting gas-vacuoles (observed also in an Amoeba by Bütschli), which serve a hydrostatic function, causing the Arcella to float. The gas can be rapidly absorbed by the protoplasm, when the vacuole necessarily disappears and the Arcella sinks.

CLASS IV. LABYRINTHULIDEA

Characters.-Gymnomyxa forming irregular heaps of ovoid nucleated cells, the protoplasm of which extends itself as a branching network or labyrinth of fine threads. The oval (spindle-shaped) corpuscles, consisting of dense protoplasm, and possessing each a well-marked nucleus (not observed in Chlamydomyxa), travel regularly and continuously along the network of filaments. The oval corpuscles multiply by fission; they also occasionally become encysted and divide into four spherical spores. The young forms developed from these spores presumably develop into colonies, but

have not been observed.

Genera.-Two genera only of Labyrinthulidea are known:Labyrinthula, Cienkowski; Chlamydomyxa, Archer.

Cienkowski (35) discovered Labyrinthula on green Algae growing on wooden piles in the harbour of Odessa (marine). It has an orange colour and forms patches visible to the naked eye. Chlamydomyxa was discovered by Archer of Dublin (36) in the cells of Sphagnum and crawling on its surface; hence it is a freshwater form. Unlike Labyrinthula, the latter forms a laminated shell of cellulose (Fig. VI. 2, c), in which it is frequently completely enclosed, and indeed has rarely been seen in the expanded labyrinthine condition. The laminated cellulose shells are very freely secreted, the organism frequently deserting one and forming another within or adherent to that previously occupied. The network of Chlamydomyxa appears to consist of hyaline threads of streaming protoplasm, whilst that of Labyrinthula has a more horny consistence, and is not regarded by Cienkowski as protoplasm. The spindle-shaped cells are much alike in form and size in the two genera; but no nucleus was detected by Archer in those of Chlamydomyxa. The encysting of the spindle-cells and their fission into spores has been seen only in Labyrinthula. Chlamydomyxa is often of a brilliant green colour owing to the presence of chiorophyll corpuscles, and inay exhibit a red or mottled red and green appearance owing to the chemical change of the chlorophyll.

FIG. VI.-Labyrinthulidea. 1. A colony or "cell-heap" of Labyrinthu'a vitellina, Cienk.; crawling upon an Alga. 2. A colony or "cell-heap" of Chlamydomyxa labyrinthuloides, Ar-her, with fully expanded network of threads on which the oat-shaped corpuscles (cells) are moving. o is an ingested food particle; at c a portion of the general protoplasm has detached itself and become encysted. 3. A portion of the network of Labyrinthula vitellina, Cienk., more hignly magnified. p, protoplasmic mass apparently produced by fusion of several filaments; p', fusion of several cells which have lost their definite spindle-shaped contour; s, corpuscles which have become spherical and are no longer moving (perhaps about to be encysted). 4. A single spindle cell and threads of Labyrinthula macrocystis, Cienk. n,.nucleus. 5. A group of encysted cells of L. macrocystis, embedded in a tough secretion. 6, 7. Encysted cells of L. macrocystis, with enclosed protoplasm divided into four spores. 8. 9. Transverse dívision of a non-encysted spindle-cell of L. macrocystis. set upon a network of threads. Such a network, whether in t condition of soft protoplasm or hardened and horny, is represented in the higher Mycetozoa by the capillitium of the sporocysts.

The most important difference between Archer's Chlamydomyxa and Cienkowski's Labyrinthula is that in the former the threads

of the network appear to consist of contractile protoplasm, whilst in the latter they are described as firm horny threads exuded by the spindle-cells. Neither form has been re-examined since its discovery; and it is possible that this apparent difference will be removed by further study

1

numerous isolated filamentous pseudopodia, which exhibit very little movement or change of form, except when engaged in the inception of food-particles. The protoplasm of the spherical body is richly vacuolated; it may exhibit one or more contractile vacuoles and either a single central nucleus or many nuclei (Nuclearia, Actinosphærium). Skeletal products may or may not be present. Flagellulæ have been observed as the young forms of some species (Acanthocystis, Clathrulina), but very little has been as yet ascertained as to spore-formation or conjugation in this group, though isolated facts of importance have been observed. Mostly freshwater forras.

a

FIG. VII.-Heliozoa. 1. Actinophrys sol, Ehrb.; x 800. a. food-particle lying in a large food-vacuole; b, deep-lying finely granular protoplasm; c, axial filament of a pseudopodium extended inwards to the nucleus; d, the central nucleus; e, contractile vacuole; f, superficial much-vacuolated protoplasm. 2. Clathrulina elegans, Cienk.; x 200. 3. Heter. ophrys marina, H. and L. x 660. a, nucleus; b, clearer protoplasm surrounding the nucleus; c, the peculiar felted envelope. 4. Raphidiophrys pallida, F. E. Schultze; x 430. a, food-particle; b, the nucleus; c, contractile vacuole ; d, central granule in which all the axis-filaments of the pseudopodia meet. The tangentially disposed spicules are seen arranged in masses on the surface. 5. Acanthocystis turfacea, Carter x 240. a, probably the central nucleus; b, clear protoplasm around the nucleus; c, more superficial protoplasm with vacuoles and chlorophyll corpuscles; d, coarser siliceous spicules; e, finer forked siliceous spicules; f, finely granular layer of protoplasm. The long pseudopodia reaching beyond the spicules are not lettered.. 6. Bi-flagellate "flagellula" of Acanthocystis aculeata. a, nucleus. 7. Ditto of Clathrulina elegans. a, nucleus. 8. Astrodisculus ruber, Greeff; x 320. a, red-coloured central sphere (? nucleus);. b, peripheral homogeneous envelope.

CLASS V. HELIOZOA, Haeckel, 1866. Characters.-Gymnomyxa in which the dominating amoeba phase has the form of a spherical body from the surface of which radiate

14

13

12

FIG. VIII-Heliozoa. 1. Actinosphærium Eichhornii, Ehr. ; x 200 a, nuclei; b, deeper protoplasm with smaller vacuoles and numerous nuclei; c, contractile vacuoles; d, peripheral protoplasm with larger vacuoles. 2. A portion of the same specimen more highly magnified and seen in optical section. a, nuclei; b, deeper protoplasm (so-called endosare); d, peripheral protoplasm (so-called ectosarc); e, pseudopodia showing the granular protoplasm streaming over the stin axial filament; f, foodparticle in a food-vacuole. 3, 4. Nuclei of Actinosphærium in the resting condition. 5-13. Successive stages in the division of a nucleus of Actinosphærium, showing fibrillation, and in 7 and 8 formation of an equatorial plate of chromatin substance (after Ilertwig). Cyst-phase of Actinosphærium Eichhornii, showing the protoplasm divided into twelve chlamydospores, each of which has a siliceous coat; a, nucleus of the spore; g, gelatinous wall of the eyst; h, siliceous coat of the spore.

14.

ORDER 1. APHROTHORACA, Hertwig (56). Characters.-Heliozoa devoid of a spicular or gelatinous envelove, excepting in some a temporary membranous cyst.

Genera.-Nuclearia, Cienk. (37) (many nuclei ; many contractile vacuoles body not permanently spherical, but amoeboid); Actinophrys, Ehr. (Fig. VII. 1; body spherical; pseudopodia with an axial skeletal filament; central nucleus; one large contractile vacuole; often forming colonies; A. sol, the Sun-animalcule); Actinosphærium, Stein (Fig. VIII.; spherical body; pseudopodía with axial filament; nuclei very numerous; contractile vacuoles 2 to 14); Actinolophus, F. E. Schulze (stalked).

ORDER 2. CHLAMYDOPHORA, Archer (57). Characters.-Heliozoa with a soft jelly-like or felted fibrous

envelope.

Genera.-Heterophrys, Archer (Fig. VII. 3); Sphærastrum, Greeff; Astrodisculus, Greeff (Fig. VII. 8).

ORDER 3. CHALAROTHORACA, Hertw. and Lesser (58). Characters.-Heliozoa with a loose envelope consisting of isolated siliceous spicules.

Genera.-Raphidiophr ys, Archer (Fig. VII. 4; skeleton in the form of numerous slightly curved spicules placed tangentially in the superficial protoplasm); Pompholyxophrys, Archer; Pinacocystis H. and L.; Pinaciophora, Greeff; Acanthocystis, Carter (skeleton in the form of radially disposed siliceous needles; encysted condition observed, and flagellula young, Fig. VII. 6); Wagnerella, Meresch.

ORDER 4. DESMOTHORACA, Hertw. and Less. Characters.-Heliozoa with a skeletal envelope in the form of a spherical or nearly spherical shell of silica preforated by numerous large holes. Genera.-Orbulinella, Entz (without a stalk); Clathrulina, Cienk. (with a stalk, Fig. VII. 2).

Further remarks on the Heliozoa. -The Sun-animalcules, Actinophrys and Actinosphærium, were the only known members of this group when Carter discovered in 1863 Acanthocystis. Our further knowledge of them is chiefly due to Archer of Dublin, who discovered the most important forms, and figured them in the Quart. Jour. Micr. Sci, in 1867.

Some of the Proteomyxa (e.g., Vampyrella) exhibit "heliozoonlike" or "actinophryd" forms, but are separated from the true Heliozoa by the fact that their radiant pseudopodia are not maintained for long in the stiff isolated condition characteristic of this group. It is questionable whether Nuclearia should not be relegated to the Proteomyxa on account of the mobility of its body, which in all other Heliozoa has a constant spherical form.

Actinophrys sol is often seen to form groups or colonies (by fission), and so also is Raphidiophrys It is probable from the little that is known that reproduction takes place not only by simple fission but by multiple fission, producing flagellate spores which may or may not be preceded by encystment. Only Clathrulina, Acanthocystis, Actinosphærium, and Actinophrys have been observed in the encysted state, and only the first two have been credited with the production of flagellated young. The two latter genera form covered spores within their cysts, those of Actinosphærium being remarkable for their siliceous coats (Fig. VIII. 14), but their further development has not been seen.

CLASS VI. RETICULARIA, Carpenter, 1862. (Foraminifera, Auct., Thalamophora, Hertwig). Characters.-Gymnomyxa in which the dominating amoebaphase, often of great size (an inch in diameter), has an irregular form, and a tendency to throw out great trunks of branching and often anastomosing filamentous pseudopodia, and an equally strong tendency to form a shell of secreted membrane or secreted lime or of agglutinated sand particles (only in one genus of secreted silex) into which the protoplasm (not in all?) can be drawn and out of and over which it usually streams in widely spreading lobes and branches. One nucleus is present, or there are many. A contractile vacuole is sometimes, but not as a rule, present (or at any rate not described). Reproduction is by fission and (as in some other Protozoa) by the formation of peculiar bud-spores which remain for a time after their formation embedded in the parental protoplasm. No multiple breaking up into spores after or independent of the formation of a cyst is known. Marine and freshwater.

The Reticularia are divisible into several orders. The marked peculiarity of the shell structure in. certain of these orders is only fitly emphasized by grouping them together as a sub-class Perforata, in contrast to which the remaining orders stand as a sub-class Imperforata. The distinction, however, is not an absolute one, for a few of the Lituolidea are perforate, that is, are sandy isomorphs of perforate genera such as Globigerina and Rotalia.

2

11.

6

10

7

8

9

1. Diplophrys

12 FIG. IX.-Gromiidea (Reticularia membranosa). Archeri, Barker. a, nucleus; b, contractile vacuoles; c, the yellow oil-like body. Moor pools, Ireland. 2. Gromia oviformis, Duj. a, the numerous nuclei; near these the elongated bodies represent ingested Diatoms. Freshwater. 3. Shepheardella taniiformis, Siddall (Quart. Jour. Micr. Sci., 1880); x 30 diameters. Marine. The protoplasm is retracted at both ends into the tubular case. a, nucleus. 5. Shepheardella taniiformis; x 15; with pseudopodia fully expanded. 6-10. Varying appearance of the nucleus as it is carried along in the streaming protoplasm within the tube. 11. Amphitrema Wrightianum, Archer, showing membranous shell encrusted with foreign particles. Moor pools, Ireland. 12. Diaphorophodon mobile, Archer. a, nucleus. Moor pools, Ireland.

4.

Fam. 2. AMPHISTOMINA, with an aperture at each end of the shell. Genera.-Diplophrys, Barker (Fig. IX. 1); Ditrema, Archer; Amphitrema, Archer (Fig. IX. 11); Shepheardella, Siddall (39) (membranous shell very long and cylindrical so as to be actually tubular, narrowed to a spout at each end, Fig. IX. 3; protoplasm extended from either aperture, Fig. IX. 5, and rapidly circulating within the tubular test during life, carrying with it the nucleus which itself exhibits peculiar movements of rotation, Fig. IX. 6, 7, 8, 9, 10).

ORDER 2. ASTRORHIZIDEA, Brady.

Characters.-Test invariably consisting of foreign particles; it is usually of large size and single-chambered, often branched or radiate with a pseudopodial aperture to each branch, the test often continued on to the finer branches of the pseudopodia (Fig. X. 12); never symmetrical. All marine.

Fam. 1. ASTRORHIZINA, Brady. Walls thick, composed of loose sand or mud very slightly cemented.

Genera.-Astrorhiza, Sandahl (Fig. X. 12, very little enlarged); Pelosina, Brady; Storthosphæra. Brady: Dendrophrya, St. Wright: Syringammina, Brady.

Fam. 2. PILULININA.

Test single-chambered; walls thick, composed chiefly of felted sponge-spicules and fine sand, without calcareous or other cement.

Genera.-Pilulina, Carpenter; Technitella, Norman: Bathysiphon, Sars.

Fam. 3. SACCAMMININA. Chambers nearly spherical; walls thin, composed of firmly cemented sand grains.

Genera.-Psammosphæra, Schultze; Sorosphæra, Brady; Saccammina, M. Sars.

Fain. 4. RHABDAMMININA. Test composed of firmly cemented sand-grains, often with sponge - spicules intermixed; tubular; straight, radiate, branched or irregular; free or adherent; with one, two, or more apertures; rarely segmented.

Genera.-Jaculella, Brady; Marsipella, Norman (Fig. X. 13); Rhabdammina, M. Sars; Aschemonella, Brady; Rhizammina, Brady; Sagenella, Brady; Botellina, Carp.; Haliphysema, Bowerbank (test wine-glass-shaped, rarely branched, attached by a disklike base; generally beset with sponge-spicules, Fig. X. 11; pseudopodial aperture at the free extremity). This and Astrorhiza are the only members of this order in which the living protoplasm has been observed; in the latter it has the appearance of a yellowish cream, and its microscopic structure is imperfectly unknown (61). In Haliphysema the network of expanded pseudopodia has been observed by Saville Kent as drawn in Fig. X. 11. Lankester (59) discovered numerous vesicular nuclei scattered in the protoplasm (Fig. X. 10, n), and also near the mouth of the shell reproductive bodies (probably bud-spores) embedded in the protoplasm (Fig. X. 8). Haliphysema was described by Bowerbank as a Sponge, and mistaken by Haeckel (60) for a very simple two-cell-layered animal (Enterozoon), to which he assigned the class name of Physemaria.

ORDER 3. MILIOLIDEA, Brady.

Characters.-Test imperforate; normally calcareous and porcel1 lanous, sometimes encrusted with sand; under starved conditions (e.g., in brackish water) becoming chitinous or chitino-arenaceous; at abyssal depths occasionally consisting of a thin homogeneous, imperforate, siliceous film. The test has usually a chambered structure, being divided by septa (each with a hole in it) into a series of loculi which may follow one another in a straight line (Fig. X. 4) or the series may be variously coiled (Fig. X. 1 and 3). The chambering of the test does not express a corresponding cell segmentation of the protoplasm; the latter, although growing in volume as the new shell-chambers are formed, remains one continuous cell-unit with many irregularly scattered nuclei (Fig. X. 2). The chambered and septate structure results in this group and in the other orders from the fact that the protoplasm, expanded beyond the last-formed chamber, forms a new test upon itself whilst it lies and rests upon the surface of the old test. The variations in such a formation are shown in Fig. XII. 1, 2, 3, 4.

FIG. X.-Imperforata. 1. Spiroloculina planulata, Lamarck, showing five. "coils"; porcellanous. 2. Young ditto, with shell dissolved and protoplasni stained so as to show the seven nuclei n. 3. Spirolina (Peneroplis); a sculptured imperfectly coiled shell; porcellanous. Vertebralina, a simple shell consisting of chambers succeeding one another in a straight line; porcellanous. 5, 6. Thurammina papillata, Brady, a sandy form. 5 is broken open so as to show an inner chamber; recent. x 25. 7. Lituola (IIaplophragmium) canariensis, a sandy form; recent. 8. Nucleated reproductive bodies (bud-spores) of Haliphysema. 9. Squammulina lævis, M. Schultze; x 40; a simple porcellanous Miliolide. 10. Protoplasmic core removed after treatment with weak chromic acid from the shell of Haliphysema Tumanovitzii, Bow. n, vesicular nuclei, stained with hematoxylin (after Lankester). 11. Haliphysema Tumanovitzii; x 25 diam.; living specimen, showing the wine-glass-shaped shell built up of sand-grains and sponge-spicules, and the abundant protoplasm p, issuing from the mouth of the shell and spreading partly over its projecting constituents. 12. Shell of Astrorhiza limicola, Sand.; ; showing the branching of the test on some of the rays usually broken away in preserved specimens (original). Section of the shell of Marsipella, showing thick walls built of sandgrains.

13.

Fam. 1. NUBECULARINA. Test free or adherent, taking various irregular asymmetrical forms, with variable aperture or apertures. Genera.-Squammulina, Schultze (Fig. X. 9, showing the expanded pseudopodia); Nubecularia, Defrance.

Fam. 2. MILIOLINA. Shell coiled on an elongated axis, either symmetrically or in a single plane or inequilaterally; two cham(addition of new chambers) at either end of the shell. bers in each convolution. Shell aperture alternately during growth

Genera.-Biloculina, D'Orb.; Fabularia, Defrance; Spiroloculina, D'Orb. (Fig. X. 1, 2); Miliolina, Williamson (Fig. XI.).

Fam. 3. HAUERININA. Shell dimorphous; chambers, partly milioline, partly spiral or rectilinear.

Genera.-Articulina, D'Orb.; Vertebralina, D'Orb. (Fig X. 4); Ophthalmidium, Kubler; Hauerina, D'Orb.; Planispirina, Seguenza Fam. 4. PENEROPLIDINA. Shell planospiral or cyclical, sometimes crosier-shaped, bilaterally symmetrical.

Genera.-Cornuspira, Schultze; Peneroplis, Montfort (Fig. X. 3)