82 



REPORT 1877. 



Besides undeterminable fragments of other and probably new species. 



The species named in the above list are 75 in number. Of these no less than 46 

 have been described by me for the first time in the ' Annals and Magazine of Natural 

 History ' for 1876 and 1877. Several of them were also procured in the ' Porcupine,' 

 ' Challenger/ and ' Voringen ' expeditions. A great many more deep-sea species 

 remain to be worked out and described by me from the ' Porcupine : expeditions of 

 1809 and 1870. 



I have not included the Pteropods in the list, although their shells occur at the 

 greatest depths — because they are oceanic, and inhabit only the surface or superficial 

 zone, their shells falling to the bottom after death and when evacuated by preda- 

 ceous animals. 



The Mollusca of very deep water or the benthal zone are certainly peculiar, and 

 constitute part of a distinct fauna, notwithstanding that some of them frequent 

 shallower water. It is very difficult to say how far they may be affected by bathy- 

 motrical conditions. An important contribution to this part of the subject was 

 made by Mr. Buchanan at a recent meeting of the Royal Society of Edinburgh, 

 in which he stated, as the preliminary result of his analysis of the sea-water 

 collected in the ' Challenger ' expedition, that as regards the percentage of oxygen 

 present at different depths, it diminishes from the surface to a depth of 300 fathoms, 

 and increases from this point to lower depths*. See also rny account of the beha- 

 viour of Trochus occidentalis, when dredged from the deep-sea zone on our northern 

 coasts, which is explained by Mr. Buchanan's statement f. 



They are not always of a small size. In the 'Porcupine ' expedition of 1869 the 

 dredge brought up, at the depth of 1207 fathoms, in the Bay of Biscay, a living 

 specimen of Fusus attenuates, which measiu'es two inches and a quarter in length ; 

 and another dredging at the depth of 2435 fathoms (nearly three miles), in the 

 same part of the Bay, yielded a living specimen of Dentalium candidum about an 

 inch and a half long. In the ' Challenger ' expedition was trav, led, at the depth of 

 1600 fathoms, in the South Atlantic (S. Lat. 46° 16', E. Long. 48° 27'), a living 

 specimen of a magnificent shell belonging to Cymbium or an allied genus, which 

 has a length of six inches and three quarters and a breadth of four inches ! And 

 during my cruise in the ' Valorous/ I dredged, at the depth of 1100 fathoms, in 

 Davis Strait, a living specimen of DenUdhnn candidum an inch and three quarters 

 long. These treasures of the deep are so apt to entrance the imagination of a natu- 

 ralist, that I have often dreamt of walking on the sea-bed and picking up unknown 

 and wonderful shells ; and in my waking hours I have envied the faculty of the 

 Argonaut in Morris's ' Life and Death of Jason/ 



" Euphemus, who had power to go 

 Dryshod across the plain no man doth sow." 



I hope it is pardonable to avail one's self of a little poetical licence to make the 

 quotation applicable to the bottom as well as to the surface of the sea. 



The distribution of the deep-sea Mollusca is unquestionably caused by submarine 

 currents, with the direction and extent of which, however, we are unacquainted. 



* ' Nature/ June 14, 1877. 



t ' British Conch ology,' vol, iii. pp. 335, 336. 



