Chap, xxii.] REMARKABLE DEEP-SEA ASCIDIAN. 



509 



appointment, but even to the last every Cuttlefish which came 

 up in our deep-sea net was squeezed to see if it had a Belem 

 nite's bone in its back, and Trilobites were eagerly looked 

 out for. 



A certain number of animal forms have been obtained in the 

 living condition from the deep sea, which were supposed, until 

 thus found, to be extinct, and to exist only as fossils ; but there 

 are a considerable number of shallow-water and terrestrial forms 

 which have similarly survived for long periods, and exist in the 

 fossil as well as in the living condition. The exploration of 

 any vast hitherto uninvestigated area must necessarily add, from 

 amongst the numerous animal forms discovered in it, some to 

 the list of those which are both fossil and recent. It has yet 

 to be shown that, in the case of the deep-sea fauna, the numbers 

 of such comparatively long-lived forms are greater propor- 

 tionately than in that of shallow-water faunas. 



Large numbers of interesting new genera and species of well- 

 known families of animals were obtained by the dredge, but 

 very few which were widely different in their essential ana- 

 tomical structure from hitherto known forms, and thus of first- 

 rate zoological importance. We picked up no missing links to 

 fill up the gaps in the great zoological family tree. The results 

 of the " Challenger's " voyage have gone to prove that the 

 missing links are to be sought out rather by more careful in- 

 vestigation of the structure of animals already partially known, 

 than by hunting for entirely new ones in the deep sea. 



The excessively wide area of the floors of the oceans in the 

 matter of production of species contrasts markedly with wide 

 areas upon the land surface, which are, as has been shown by 

 Mr. Darwin,* specially favourable to the development of varia- 

 tions and the production of new forms. 



The deep-sea animals obtained by the ship are now in the 

 hands of various specialists for description, and are as yet only 

 partially reported on.t As far as I can judge from cursory ex- 

 amination of what was dredged, I believe that the most aberrant 

 and important new animal obtained by the " Challenger's " 

 deep-sea dredgings is an Ascidian, which I have described under 

 the name of Octacnemus By thins. X 



The animal, of which a figure of one-half the natural size is 

 here given, is of a most remarkable form for an Ascidian, having 



* "Origin of Species," lOth Ed., p. 83. 



t These reports are now complete (1892). See " Report.^ of the Ex- 

 ploring Expedition of H.M.S. ' Challenger.' Zoology " (G.C.B.). 



I H. N. Moseley, "On Two New Forms of Deep-Sea Ascidians ob- 

 tained during the Voyage of H.M.S. ' Challenger.' " Trans. Linn. Soc, 

 2nd Ser. Zoology, Vol. I., p. 287. 



