August J, 1884.] 



SCIENCE. 



103 



intestines, which open at the other end of the crea- 

 ture, are the orifices of branching tubes forming the 

 respiratory organs. When holothurians are disturbed 

 (as on being caught, for instance), they contract, and 

 suddenly shoot out their viscera. But what is more 

 singular and inexplicable is, that after some time 

 these organs are reproduced. It would seem that the 

 life of these animals, at whatever depth, would pass 

 in perfect quiet; yet the holothurians living near the 

 surface, as well as those between four and five thou- 

 sand metres, are harassed by a swarm of parasites. 

 Thus some of them, as Van Beneden says, are trans- 

 formed into a kind of living hotel; some lodge in 

 their respiratory organs little fishes (Ferasfer) with a 

 body as long as that of an eel, but contracted; others 

 shelter one or more couples of the little crabs called 

 Pinnotheres, or carry in their intestines the worms 

 called Anoplodium. But besides these parasites, 

 which do not live at the expense of the host, of whom 

 they demand only a home, there are others which 

 live on the host. 



Perrier says, "A holothurian has essentially the 

 form of a five-sided melon with an opening at each 

 extremity. With holothurians of great depths, how- 

 ever, this form almost entirely disappears. Some 

 curve themselves back into a U-shape; others, as 

 Ankyroderma, have the form of an ovoid sac, without 

 the ambulacra which cut the surface of the other 

 holothurians into five arms; the majority, instead 

 of the characteristic radial symmetry of their allies, 

 present a bilateral symmetry as distinct as that of the 

 worms and the vertebrates, and creep on the mire by 

 means of a ventral sole, like slugs, forming a peculiar 

 example of the mode in which two organic types 

 which seem separated by an unbridgable abyss may 

 be found in the same animal." 



The sea-urchins are represented at great depths 

 by forms very varied, and peculiar to certain zones. 

 Some are remarkable for the development and beauty 

 of their spines. For a very long time the remains of 

 a genus of echinoderms called Calveria had been 

 found in cretaceous deposits; but only in 1869, during 

 the cruise of the Porcupine, was the survival of this 

 form at the bottom of our seas revealed to us. " As 

 the dredge was coming in," says Thomson, speak- 

 ing of this form, " we got a glimpse from time to time 

 of a large scarlet urchin in the bag. We thought it 

 was one of the highly coloured forms of Echinus 

 Flemingii of unusual size; and as it was blowing 

 fresh, and there was some little difficulty in getting 

 the dredge capsized, we gave little heed to what 

 seemed to be an inevitable necessity, — that it should 

 be crushed to pieces. We were somewhat surprised, 

 therefore, when it rolled out of the bag uninjured; 

 and our surprise increased, and was certainly in my 

 case mingled with a certain amount of nervousness, 

 when it settled down quietly in the form of a round 

 red cake, and began to pant, — a line of conduct, to 

 say the least of it, very unusual in its rigid undemon- 

 strative order. Yet there it was, with all the ordinary 

 characters of. a sea-urchin, its interambulacral areas, 

 and its ambulacral areas with their rows of tube feet, 

 its spines, and fine, sharp, blue teeth; and curious un- 



dulations were passing through its perfectly flexible 

 leather-like test. I had to summon up some reso- 

 lution before taking the weird little monster in my 

 hand." 



The flexibility of the sides of this particular 

 echinus, as was discovered, is due to a peculiar ar- 

 rangement of the pieces forming the test. As for 

 the palpitation which seems to have so impressed the 

 English naturalists, it is simply due to the ship's roll- 

 ing or pitching, or else to the vibrations arising from 

 the action of the engines on board. 



A group most abundant in new forms is composed 

 of the beautifully formed and often brilliantly col- 

 ored animals called star-fishes. Attention must be 

 directed first to Brisinga, which sometimes has as 

 many as twenty long, flexible arms. These brilliant 

 orange-red stars often violently detach their arms 

 when they feel themselves caught and drawn up by 

 the movement of the trawl; and it is very rarely 

 that they can be studied in an uninjured state. Abs- 

 jornsen, who first discovered them on the coast of 

 Norway a little above Bergen, at a depth of 200 fath- 

 oms, much admired the phosphorescent light shed by 

 the body and the arms. " Whole and uninjured as I 

 saw it once or twice under the water in the dredge, 

 this animal is peculiarly brilliant, a veritable gloria 

 maris ;" and he accordingly gave it the name Brisin- 

 ga, from a jewel of the goddess Freya. Brisinga 

 coronata was obtained at the tropics, hitherto found 

 only in the German ocean. In the cruise of the Por- 

 cupine it was found at 914 metres. We found it 

 between 736 and 1,435 metres. Other species occur at 

 depths ranging from 882 to 3,455 metres. All these 

 forms are new, and so abundant that thousands 

 cover the bottom of the sea. 



Crinoids, the last echinoderms of which we shall 

 speak, are cup-shaped. From the edges extend sim- 

 ple arms, bifurcated or branched, with pinnules at 

 the sides. From the back grows a jointed rod, which 

 attaches itself to surrounding objects. In Antedon 

 and Actinometra, represented on the plate, this rod 

 exists only during an early stage, the body becoming 

 free at a certain point in their development; while 

 with Pentacrinus, also figured, and with Democrinus 

 and Bathycrinus ; it continues during the life of the 

 animal. The crinoids have always been considered 

 by naturalists interesting objects of study, as much 

 on account of their rarity in the present marine 

 fauna, as on account of their great abundance in very 

 old geologic periods. In fact, these animals, which 

 were common during the Silurian period, increased 

 in numbers at the time of the calcareous carbonif- 

 erous deposits, which are formed almost exclusively 

 of beds composed of their remains. They were found 

 again in abundance in that middle horizon of the 

 triassic deposits called muschelkalk. After this time 

 of extraordinary prosperity, crinoids appear, as 

 Thomson says, to have gotton the worst in the strug- 

 gle for existence. As they approach the present 

 period, the species become rarer, and are represented 

 by fewer individuals. At one time it was thought that 

 Antedon alone existed at the present time. The dis- 

 coveries made in the deep-sea explorations resulted 



