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other little fish, which start back from contact with Actinia and Sagartia, rest placidly on the portions of Peachia that extend above the sand.
We found this species very easy to keep in captivity: even those specimens which we injured in digging up survived a considerable time. It is by no means necessary to have sand for them to burrow in. They will lie free at the bottom, and expand themselves to their full length. One that we measured attained the length of four and a-half inches.
One specimen which we had in confinement ejected a quantity of ova. These were small spherical bodies, furnished with short stiff hairs or bristles, sticking out straight from the whole surface. These hairs did not move like cilia.
The smallest Peachia hastata that we found measured, when extended, one inch in length. Its conchula was precisely the same as that figured by Gosse (Actin. Brit., p. 239), as belonging to P. undata : except for its size and the shape of its conchula this little specimen was exactly the same as all others that we found, and we are inclined to look upon it as being merely an immature Peachia hastata. We may add that the alternating opaque white markings on the margin, which Gosse mentions as characteristic of Peachia undata were present in all the specimens of Peachia hastata that we found. Possibly it may be found necessary to place Peachia undata under Peachia hastata.
EPIZOANTHUS, sp. The description given by Gosse of Zoanthus couchië is very general, and would include many forms which subsequent authors would probably refer to distinct species.
We have obtained at Dalkey Island from between the tide marks an Epizoanthus which would possibly have been placed by Gossel in this species (Actin. Brit., p. 297), though the specimens which we found were very much larger than those whose measurements that writer has given, the polypes being in height quite one-half inch in length from where they emerged from the cænenchyma to the top of the column, and in diameter reaching in the column one-third of an
Professor Haddon, to whom we have submitted the specimens we obtained at Dalkey Island since this report was written, considers them to belong to a new species which he has named Epizoanthus wrightii. His account of the species will shortly appear in a Paper by him and Shackleton in the Transactions of the Royal Dublin Society.
inch, and in the disk one-half of an inch, while the tentacles, when fully extended, attained the length of half an inch. The number of tentacles was thirty-two, in two rows of sixteen each, instead of (as Gosse gives) twenty-eight, in two rows of fourteen each. The margin of the column was cut into sixteen teeth. The mouth was a narrow slit, with only one groove. In colour we found two varieties : one, dirty pellucid white; the other, orange pink. In both varieties the disk was speckled with opaque white, and the tentacles tipped with the same colour. When not fully extended, the tentacles exhibited transverse corrugations. All the specimens we found sprung from a broad, flat, irregularly-shaped cænenchyma, which adhered to the encrustations on granite boulders, but never to the granite itself. In August we saw one specimen with yellow ciliated bodies (planulae ?) floating in the tentacles. These bodies were irregular in shape, and kept continually changing their outline. When irritated this anemone ejects its craspeda ; these organs are coloured, according to the varieties, either white or orange pink.
The transverse sections which we cut showed that these Dalkey specimens possess sixteen pairs of mesenteries arranged according to Erdmann's "macrotypus.”
The differences existing between the Dalkey specimens and the description of the species given by Gosse induce us to believe that his description must have been based on the examination of immature forms, or else that the specimens we found belong to a new and distinct species.
HYAS ARANEUS. There has lately been a good deal of discussion relating to the habit this crab has of clothing itself with corallines, shells, and other foreign bodies (Nature, vol. xli., between pp. 176 and 586 : also Plymouth Marine Biological Journal). Those who have written about the matter seem to be of opinion that this habit serves the crab as a protection by rendering it hard to distinguish it from its environment. We believe that the decorations which the animal assumes are useful to it by helping to furnish it with the means of catching its prey. We proceed to state the observations which induced us to form this belief. First of all, there can be no doubt that the crab arrays itself in this curious fashion with a view to concealing itself the more easily. For even though it be quite covered with one disguise, if you move it into a new environment it promptly assumes a new disguise to suit its changed surroundings. For instance, we obtained three specimens of
ans of catch to form the itself in
this crab all dressed alike in short sea-weeds, and one evening placed one of them among stones covered with Sertularia abietina and Hydrallmania falcata, another among some small shells and fine gravel, and the third among a large number of specimens of Antedon rosaceus. In the morning each of them had clothed himself to suit his environment. No. 1, who had been placed among the corallines, had arrayed himself with a dense shrubbery of Sertularia abietina on his back, with the finer branches of Hydrallmania falcata on his legs. He then climbed an empty valve of the shell of Solen ensis, which stood nearly upright in a corner of the tank. On the top of this shell he propped himself, his chief support being his last pair of legs, his chelae being stretched prominently forward, and the forceps (formed by the two terminal joints) being held wide open and conspicuously displaying its polished white and red tips. But though he maintained his position on the shell for the whole day, he did not remain motionless. On the contrary, he kept swaying himself to and fro with an almost rhythmic motion, every limb remaining rigid save the hindmost legs, whose basal joints formed the places from which the motion started. The following day this Hyas descended from his elevated position, and took up his post among the branches of the Sertularia abietina, and here he remained swaying himself to and fro as before. This last position seemed to suit him better, and he occupied it for several days, indeed for all the rest of the time that he was in the tank.
No. 2, who had been placed among the small shells and fine gravel covered himself with these materials, and No. 3, who was given as a companion to the crinoids, broke off portions of their arms and fastened them on his back using the cirri to conceal his legs. They both assumed similar positions and exhibited similar motions to those described in the case of No. 1.
So far, then, we are doing the Hyas no injustice in imputing to him the intention of concealing himself when he makes his choice of clothing. But what is the meaning of the rhythmic motion of his body and his stilted attitude ? A fortunate accident enabled us to determine this. A few days after we obtained the Hyas we put a number of gobies into the tank. These little fish had their curiosity at once aroused by the red and white tips of the chelae moving among the groves of Sertularians, and swam up to observe such an interesting phenomenon. The moment one came within his reach the Hyas suddenly closed all his extended legs like a spring trap, and generally succeeded in making a capture of the poor goby, who was forthwith thrust head-foremost into the mouth of his voracious captor. One Hyas caught and ate fourteen gobies within a week. We believe, therefore, that the polished white and red tipped chelae, the two terminal joints of which are never concealed by the decorations, are held aloft by the crab as a kind of bait, and that the rhythmic motion is added to make the bait still more attractive. It is needless to remark that the capture of the fish is rendered much more easy by the way the crab has himself disguised, so that he is almost unrecognizable among his surroundings. It is quite consistent with the concealment being adopted for the purpose of procuring food that it should also serve to protect the Hyas in its turn from becoming a prey to other animals. But we have never had any animals in the tank which ventured to attack Hyas araneus or H. coarctatus. It is stated by Bell (British Stalk-eyed Crustaceans, p. 34) that H. araneus is preyed upon by cod-fish.
whether which histe quiet ly steen"
We kept an Eledone cirrosa which we found on the strand at Monkstown for some weeks in the tank. Our specimen was a good rich coral red or crimson, though, of course, continually changing in intensity of shade, and its body was nearly always variegated with paler or even white spots. The colour on the arms was less decided than on the body, and the under sides of the arms which bore the suckers were always white. Frequently, too, the outer portions of the body and the extremities of the arms became a bright iridescent green. The body underneath was always paler than above, and the under side was frequently green instead of red, like the extremities. When it lay quite quiet in the tank, lurking behind a large stone in a corner which it made its home, it generally assumed its palest hues : when on the alert and roving through the tank it was generally its deepest crimson.
All the time that it was with us we are not aware that it ate anything; we supplied it plentifully with shrimps, gobies, and crabs, and though it sometimes seized these animals with its arms it always released them uninjured. We tempted it also with pieces of mussel, but it would not touch them.
The activity of this animal makes it a very pleasing object in a marine aquarium. The grace of its motion has been observed by Johnson (Proc. Berw. N. H. Club, i., p. 198), and by J. Gwyn Jeffreys (British Conchology, vol. v., p. 146). We believe the ease and steadiness of its morements as it propels itself backward by ejecting water from the funnel are largely due to the position in which it folds its arms, always keeping the bases of two of them—one at either sidesharply projecting, so as to make a pair of lateral keels.
When at rest the arms are coiled backward in curls at the tips; and the animal keeps hold of whatever it is attached to by only one or two of the larger suckers which surround the mouth. When in this state the length of the arms is considerably reduced, and the suckers may appear to be set in a double row as in Octopus vulgaris, with which this species appears to have been sometimes confounded (Haddon, The Zoologist, 3 ser., vol. x., p. 4). When the arms are extended, however, the suckers are seen to be manifestly set in a single row, and so determine the genus by a characteristic known to Aristotle (H. A., iv., vol. i., p. 525, col. i., 1. 15: ed. I. Bekker).