April 15, 1880] 



NATURE 



57i 



the sea surface when young in all the pleasures of warmth 

 and sunlight, sink when fully grown to lead a sluggish life 

 on the cold and dismal bottom. Here (Fig. 13) is a remark- 

 able deep-sea fish. It is nearly allied to the Angler of our 

 aquariums. It was found dead off the Greenland coast, 

 but closely similar fish were obtained by the Challenger 

 in great depths down to 2,400 fathoms all over the world. 

 Mr. Agassiz also got plenty of them. The fish has a very 

 near ally which lives on the surface amongst the gulf- 

 weed, from which it builds curious ball-like nests. You 

 see the fish has no ventral fins, and must be, like its 

 surface relative, a very feeble swimmer. It has very 

 small eyes and a huge mouth, and on the top of its head 

 is a lure set on a movable stalk, with which, like the 

 Angler, it attracts its prey within reach of its mouth. The 

 fish is black all over, as are most deep-sea fish, except on 

 the lure. This is composed of numerous tentacle-like 

 branches, which are covered with white spots, probably 

 phosphorescent, when the animal is living. At the bases 

 of the branches are two horn-like appendages which are 

 white, probably also phosphorescent. The fish most 

 likely thus manufactures its own light, whilst its tentacles, 

 spangled with bright spots, swayed to and fro, no doubt 

 jure many a victim to destruction. This fish is sixteen 

 inches in actual length. 



Here (Fig. 14) is what Prof. Liitken, from whom these 

 figures are taken, 1 believes to be the voung of this curious 



Fig. n.— Young Himantolophus (Rheinhardtii ?) from the stomach of an 

 Albacore. 



fish. It was found in the stomach of an Albacore Thynnus, 

 a surface-living predatory fish which was caught in the 

 tropical Atlantic. You see the little fish has, like the 

 adult, no ventral fins. The eye is very much bigger in 

 proportion than in the adult, but that is merely an in- 

 stance of retention in the young of what has been nearly 

 lost in the adult by disuse. Certain deep-sea blind Crus- 

 tacea similarly have young with fully-developed eyes. 

 The lure on the head is just growing. 



If the animal is not the young of the species just shown, 

 which probably extends from Greenland to the tropics in 

 the deep sea, it is certainly that of some closely-allied 

 form. The young of other deep-sea fish have been found 

 in the stomachs of Albacores. The young of most shallow- 

 water bottom-living fish, such as the Angler and the 

 flounder, pass their early existence at the sea-surface. If 

 this deep-sea fish really develops in the early stage at the 

 surface, how do the eggs reach the top of the water? 

 Possibly they rise slowly from fie bottom. Perhaps some 

 other deep-sea animals go through their early stages at 

 the surface. 



According to Prof. Geikie - the deep ocean basins date 

 from the remotest geological antiquity, and Dr. Carpenter 

 in his late lecture here maintained the same conclusion. 

 Whether such be the case or not, any changes which may 

 have taken place converting deep seas into shallow must 

 have occurred very slowly, so that ample time for 

 migration of deep-sea forms to fresh deep seas must have 

 been afforded. Why is it therefore that very many ancient 

 forms do not occur in the deep sea ? If the ancient deep 

 sea had been colonised say in the Silurian or Devonian 



1 "Vidensk. Selsk.-Skr." 5 le Rackke, me Bd. v. p. 319. 

 3 Loc. cit. p. 428, 



epochs, we should expect to find in its vast area many 

 remnants of the fauna of that age and of subsequent 

 geological epochs ; and such was the conclusion of the late 

 Prof. Agassiz, and of many other naturalists. It was 

 expected that all kinds of ancient forms would be brought 

 up by the deep-sea net. Contrary to anticipation, the 

 deep-sea fauna is mainly composed of more or less 

 modern shallow-water genera and their allies. The fish 

 of the deep sea comprise amongst them no Dipnoi, no 

 Ganoids, and no lampreys ; they are allies of the cod, the 

 salmon, and the Angler. There are no Trilobites in the 

 deep sea, and no Graptolites, no Bellemnites. All the most 

 ancient forms which now survive occur in shallow water. 

 Lingula, most ancient of all, is abundant in two or three 

 feet of water, and has, I believe, never been found below 

 ten fathoms. Trigonia and Limulus survive in shallow 

 water, and so do Amphioxus and'Cestracion. Heliopora, 

 the only living representative of a vast number of 

 pateozoic corals, is a shore form. 



It is true that corals which come within Milne- 

 Edwards's definition of the Rugosa occur in deep water, 

 but that group needs great modification, and the structural 

 difference between the deep-sea forms and ordinary 

 Caryophyllias is probably of comparatively little zoological 

 importance. 



Though stalked Crinoids occur in deep water, they are 





Fig. 15.'— Deep-sea Ascidian {Octacnemus Bythius). Above.— The animal 

 viewed from below; of one half [he natural siie. The nucleus is seen 

 in the centre through the transparent base of the "animal, p, pedicle of 

 attachment; B. exhalant orifice; R, rectum. Below. — Diagrammatic 

 section through the middle line of the animal's body. a. inhalant 

 orifice; H, muscle attached to nucleus ; other letters as in figure above. 



also found in a depth of only forty fathoms. There are a 

 certain number of forms in the deep sea which do not 

 occur now in shallow water, and do occur as fossils in the 

 chalk or elsewhere, but they do not form a very high per- 

 centage of the total number. 



We might have expected to find surviving in the deep- 

 sea missing parts of the branches of the zoological family 

 tree, animals of ancient pedigree which might for example 

 have explained the affinities of the Bryozoa or the 

 Brachiopoda, but scarcely a single animal thus of first- 

 rate zoological importance was obtained in great depths. 

 This is a most extraordinary fact, for in our deep-sea 

 dredgings we have explored for the first time nearly three- 

 quarters of the earth's surface. 



The most important new animal, zoologically speaking, 

 obtained from deep water by the Challenger Expedition is, 

 as far as I know, this Ascidian (Fig. 15), which I have 

 named Octacnemus. Most of its body is transparent. It 

 has eight radiate arms. Its viscera are gathered together 

 into a small nuclear mass as in Salpa, but the nerve 

 ganglion lies on the mass. The animal is attached to 



■ From H.U. Moseley, "Notes by a Na'uralist On; the [Challenger,. 

 p. 588. (Macnullan and Co., 1879.) 



