marginal. The peristome lies in a depression opposite the disk, but is unfortunately concealed by hard matrix. Affinities and differences.-The oblong form, tumid sides, and shorter ambulacra distinguish this species from E. hemisphæricus. The convexity of the base, and equality in the width of the ambulacra, afford likewise good characters by which these two allied species may be distinguished from each other. Stratigraphical position.-("This species is not at all uncommon in bed No. 5, but, from the hardness of the rock, is by no means easily extracted. I have often seen it, associated with Scutella subrotunda.' A. L. A.) It is found in the Molasse (Miocene) of several departments in France, and in the Canton of Neufchâtel, Switzerland. Collections.-Museum of the Geological Society; my cabinet. Genus AMBLYPYGUS, Agassiz, 1840. Urchins in general large, with a depressed ovoid test and a rounded border; ambulacral areas unequal in width and length; poriferous zones very narrow, extending from the disk to the peristome; base concave and arched; mouth-opening near the middle; peristome oblique, angular, without any poriferous petals. Vent large, pyriform, situated at the base, between the mouth and the border. Apical disk small, nearly central, with four ovarian pores. This genus resembles Pygaulus in the general form of the test, but is distinguished by the position of the vent, which always occupies the base between the peristome and the border; the poriferous zones are simple throughout, and are not petaloid around the peristome. The narrowness of the poriferous zones and the absence of oral lobes and petals serve to distinguish Amblypygus from Conoclypus. All the species are extinct, and found in the Tertiary rocks. 18. AMBLYPYGUS MELITENSIS, Wright, sp. nov. Pl. XXI. figs. 3a-3c. Test elongated, depressed, border inflated; ambulacral areas narrow, unequal in width, the single ambulacrum narrowest; poriferous zones very narrow; pores a little more apart on the upper surface than at the border; base concave, arched in the anteroposterior direction; mouth-opening nearly central, oblique, and angular; vent oblong, occupying the space between the peristome and the border. Dimensions.-Length 1 inch; breadth 14 inch; height inch. Description. This beautiful little Urchin might be mistaken for a Pygaulus, if the position of the vent were overlooked; it has a regular ovoid form, convex and depressed above, concave and arched below; the ambulacral areas are narrowly lanceolate and of unequal width, the ambulacrum being the smallest, and the anterior pair the widest. The poriferous zones are very narrow, and the pores appear to be a shade more apart on the upper surface than they are at the border or base. The interambulacra are likewise unequal in width, the sides are tumid, and the border is rounded. The base is convex at the sides, and concave towards the centre, where the two openings of the test are situated; it is likewise slightly arched from front to back. The peristome is nearer the anterior border; its form is indistinct from adherent matrix; it appears to be oblique and angular. The poriferous zones descend to the margin without doubling. The vent is large and oblong, one extremity approaching the peristome, the other reaching nearly to the border, and occupying much of the basal portion of the interambulacrum. The apical disk is small and excentral, with four ovarian pores; the tubercles are small, equal, and closely set. Affinities and differences.-It resembles A. apheles, Ag., from the ferruginous Nummulitic bed at Verona; but it differs from that species in having the test a regular ovoid, not tapering behind, and in possessing a larger vent. Stratigraphical position.-Collected from bed No. 1, the Upper Limestone, at Malta, where it is extremely rare. 19. CONOCLYPUS PLAGIOSOMUS, Agassiz. Stratigraphical position." I have met with this Urchin pretty often in the red and yellow Sand-bed No. 2, chiefly in the redder portions. The specimen from No. 4 I am disposed to consider specifically identical with those from No. 2. It is rare, and when met with is usually seen in fragments. All I have found have been in the nodule-beds of No. 4. The difference in shape of the specimens in the collection is evidently the result of pressure." (A. L. A.) Collections and localities.-Bristol Museum; Royal School of Mines; Earl of Ducie's Coll. ; my cabinet. Balistro, Corsica; Molasse du Cap Couronne, près Martigues (Michelin); d'Alicante (Deluc); Faredjah and Santarieh, west of Egypt (Desor). 20. HEMIASTER COTTEAUI, Wright. Stratigraphical position.-" Collected from bed No. 4, the Calcareous Sandstone, at Malta. I have not found it in any collection of Miocene fossils. What appears to me a specimen of this Urchin from No. 1 bed is, however, a very imperfect example. The specimens from beds Nos. 4 and 5 certainly belong to this species; should there be any doubt as to that from No. 1, we had better discard it and wait for more authentic information. H. Cotteaui is a common Urchin in No. 4, and is nearly always associated with H. Scilla, especially in the weather- and surf-worn rocks around the harbour of Valetta, where it may be seen in groups on the shelving parts, with the ambulacral surfaces lying uppermost, as if the animals had died where they are now found. I may remark that this is generally the case with all Echinoderms of No. 4, excepting those in the nodule-beds, where the fossils are all jumbled together. It is met with in the nodule-beds, also in the upper portions of No. 5, where it is common." (A. L. A.) 21. HEMIASTER SCILLE, Wright. Stratigraphical position." This Urchin is common in No. 4 with the other species of the genus just named. It is also plentiful in the transition and upper portions of No. 5; but all the specimens I have met with hitherto from the latter bed have been very small. It is also common in the nodule-beds of No. 4." (A. L. A.) 22. BRISSOPSIS DUCIEI, Wright. Stratigraphical position.-"All the specimens have been collected from the Upper Limestone No. 1, and its white sandstone-stratum, where the Urchin is very uncommon." (A. L. A.) Collections.-Earl of Ducie's Coll.; Museum of the Geological Society; my cabinet. 23. BRISSOPSIS GRATELOUPI, Sismonda. Stratigraphical position.-"This Urchin is common in bed No. 4, and its nodule-beds immediately overlying No. 5, associated with Hemiaster Scille, Wright, and H. Cotteaui, Wright. It is likewise found in the upper portion of No. 5." (A. L. A.) Collections.-Museum of the Geological Society; my cabinet. 24. SCHIZASTER SCILLE, Desmoulins. Stratigraphical position.-If I am correct as to the determination. of the specimens I have thus named, there are in Dr. Leith Adams's collection representatives from beds Nos. 1, 2, 4, and 5. The large specimens from No. 1 abound in the white calcareous sandstonestratum of that bed, and are most usually associated with Oysters, Pectens, &c., to be noticed hereafter. I have furnished a series of No. 1 specimens to show their gradation. The apical disk in several is much nearer the centre of the test than in others. "This Urchin appears occasionally in the black and yellow sand at its passage into the subjacent clay (No. 3); the specimens are similar to those from No. 4, both in size and configuration, excepting one description, of which I have sent several specimens; in these the single ambulacrum is not nearly so broad; and I have not seen any from the calcareous sandstone or the overlying bed which equal in size those from No. 1. There are likewise several from the nodular bed of No. 4, all small or young specimens. The single individual from No. 5 is the only one I have seen. I procured it from the Lower Limestone at the fault or gorge of Air Selina, Gozo. Like the others it differs in some particulars from the type-specimens of the upper rock, and possibly I may be incorrect in my diagnosis, and have been confounding different species with each other." (A. L. A.) Collections. In almost all collections of Maltese Echinoderms. 25. SCHIZASTER PARKINSONI, Defrance. Stratigraphical position." Of this I have sent a series. There are specimens from No. 1, where it is rare. It is the most common Urchin in No. 4, where it will be seen there is some variety. I have found it not easy to distinguish at all times between specimens of S. Desori and this species. There are ten broken specimens from No. 5 bed, which I take to be this species; but in case of error I will attempt to procure more perfect individuals from that bed.” (A.L. A.) Collections.-Royal School of Mines; British Museum; Bristol Museum; Museum of the Geological Society; Earl of Ducie's cabinet. 26. SCHIZASTER DESORI, Wright. Stratigraphical position." All my specimens are from No. 4 bed, where this Urchin is not uncommon, and is usually associated with Hemiaster Scilla, H. Cotteaui, and Brissopsis Grateloupi, also Schizaster Parkinsonii and Prenaster excentricus." (A. L. A.) Collections.-Common in all collections of Maltese Urchins. Genus BRISSUS, Aristotle, Klein. Large Urchins with an ovoid or elongated test; ambulacral summit very excentral, and ambulacrum rudimentary; anterior pair of ambulacra deeply sunk and nearly transverse; posterior pair forming an acute angle with the anterior pair and directed backwards, they are sinuous and concave; the peripetalous fasciole closely embraces the ambulacral pairs, and forms an arch on the anterior border; the subanal fasciole describes a cordate figure below the vent, which is large, oblong, and vertical. Apical disk small, four genital pores. Madreporiform body elongated between the plates. Mouth near the anterior border; peristome labiate on the posterior border. This genus comprises living and fossil species; the latter are found only in the Tertiary formations, and are chiefly of Miocene and Pliocene age. 27. BRISSUS LATUS, Wright. Distinctive characters.-The breadth of the test; the depression of the upper surface; the depth of the ambulacra, the anterior pair being less transverse, and the posterior pair more expanded than in the other species; the ambulacral summit is more central, and the anteal sulcus deeper than in its congeners. Stratigraphical position.—I have only found this Urchin in No. 1, and chiefly in the lower or coralline stratum, where in certain localities it is not uncommon, and usually met with in a fragmentary condition. Several good specimens have been found in the above stratum at the fault in Forn-i-riale Bay, where the accompanying specimens were discovered. What appear to be the spines of this Urchin are seen on the under surface of the broadest of the specimens. Collections.-Museum of the Royal School of Mines; Earl of Ducie's cabinet; Museum of the Geological Society; and my cabinet. 28. BRISSUS CYLINDRICUS, Agassiz. Stratigraphical position." Allowing for the effects of pressure, there is evidently some diversity in the configuration of the specimens, chiefly in the dorsal surfaces, which appear flatter in some than in others. This Urchin is common in the coralline stratum of No. 1, especially on certain cliff-exposures on the south coast. is often associated with Brissus imbricatus (so named and sent). There does not appear to be any difference between the specimens from Nos. 1 and 5 in the collection. It "This Urchin is not uncommon in the upper portion of No. 5. The different colouring of the tests is the result of the colour of the rock. The white specimens were from the white stratum; the reddish from the red coralline limestone above the red sand, where the two blend almost imperceptibly; the darker, from the soft drab-coloured rock, often found overlying the clay, where No. 2 is seemingly wanting. The bed No. 2 is not apparently uniformly distributed over the Island. "I have not hitherto met with this Urchin in any of the other beds." (A. L. A.) Collections.-Museum of the Royal School of Mines and of the Geological Society; Marquis of Northampton's, the Earl of Ducie's, and my cabinet. 29. BRISSUS IMBRICATUS, Wright. Pl. XXII. fig. 2. Affinities and differences.-It differs from all the preceding species in having the anterior pair of petaloid ambulacra directed obliquely forwards and outwards, and with the posterior pair forming a St. Andrew's cross on the dorsum or upper surface. It differs from Brissus Scilla in having a depressed test, with the base much more highly ornamented, and likewise in the direction of the anterior ambulacra. Stratigraphical position.-Both specimens were collected from bed No. 1, the Upper Limestone, at Malta. Collections. The Bristol Museum contains the type, and the Museum of the Geological Society of London the most perfect specimen. 30. BRISSUS TUBERCULATUS, Wright, sp. nov. Pl. XXII. fig. 1. Test ovoid, depressed, tapering behind; the two pairs of petaloid ambulacra long, narrow, lanceolate, and extending over two-thirds of the dorsum; anterior pair curved forwards, posterior pair directed outwards and backwards; poriferous zones wide, depressed; interporiferous zone convex ; peripetalous fasciole narrow; anterior border, sides, and upper surface, within and without the peripetalous fasciole, covered with large crenulated and perforated tubercles, among which smaller ones are scattered; no anteal sulcus; posterior border slightly truncated; vent large, oblong; subanal fasciole having a cordate figure beneath the opening. Dimensions.-Length 5 inches; breadth 44 inches. These measurements are only approximate, as the two specimens I have are both much distorted. Affinities and differences.-This species differs from all the other Miocene species of Brissus in having much larger tubercles on its upper surface from B. latus, Wright, in having the ambulacra level with the surface, and no anteal sulcus; the same characters distinguish it from B. cylindricus, Ag. ; and it differs from B. imbricatus, Wright, in having large tubercles without as well as within the peripetalous fasciole. The tuberculated character of the upper surface is a good diagnostic character. The imperfection of the only two fragments I possess prevents a more extended comparison with other forms. |