OF CONCHOLOGY. 



95 



of the forms which have been named as species will be consoli- 

 dated. This is especially likely to be the case in the genera 

 Odostomia, Bittium, Lacuna, Cerithiopsis, Scalar ia and others. 

 Some now considered distinct will probably be found identical 

 with North Atlantic species ; while, on the other hand, I am con- 

 vinced that many of the forms which have been considered iden- 

 tical with European Crag fossils, will prove, on examination of 

 larger series, to be quite distinct. 



I am also impressed with the belief that the zoological prov- 

 inces of the coast, from Panama to Bering Sea, will require much 

 modification. There seem, indeed, to be but two well-marked 

 faimre — one, the Northern, merging into the Indo-Pacific in the 

 Japanese seas, and into the Middle American in the vicinity of 

 San Diego or somewhat south of it ; and the Middle American 

 fauna, from that region to the coast of South America. Beside 

 this we have the Boreal or Circumpolar Province. The two for- 

 mer are at best of subordinate rank, and, with that of South 

 America, may form a Pacific, in contradistinction to the Indo- 

 Pacific Province. 



That the distribution of mollusks and other marine animals is 

 governed principally by temperature and not by depth, is no 

 new theory. I became convinced of its truth after a short 

 experience in dredging in the North Pacific, and every new 

 investigation adds weight to the same view, which, after the 

 various deep-sea explorations, may be taken as proven. I long 

 since showed that the cod, the sea-bear and sea- lion, beside other 

 marine vertebrates, are affected by similar influences. 



That temperature is not the sole agent in determining their 

 distribution must, however, be conceded. Something is due to 

 the character of the bottom, something to the supply and nature 

 of their sustenance, and something to those mysterious geogra- 

 phical laws, of whose workings we have as yet only a bare 

 inkling, in Ornithology, but which cannot remain much longer 

 without elucidation. 



Class CEPHALOPODA. 



ARGONAUTID^E. 



Argonauta Pacifica, Dall. 



Argonauta Pacifica, Dall, Am. Nat. iii, p. 237, 1869. 



Argonauta argo, Cooper, not Linne. 



? Argonauta argo, Rve., Conch. Icon. fig. 2 c. 



I have elsewhere stated my opinion that the Argonaut, so 

 common at certain periods on the coast of California, is entirely 



