186 BULLETIN OF THE 



beginning near the shores and extending to the abysses, while most 

 deep-sea dredging parties have ceased work as soon as they came into 

 comparatively shallow water, for fear of confounding what were sup- 

 posed to be two sharply differentiated faunse. We learn from the work 

 of the " Blake " that the differentiation is much less marked than would 

 be anticipated, and that, in addition to the species found widely dis- 

 tributed over the floor of ocean, there is an important contingent of 

 species which are probably derived from the adjacent litorale, as well 

 as a tolerable number which are found in water of all depths, from a few 

 fathoms on the Florida coast to two thousand fathoms iu the adjacent 

 deeps, without affecting their external characters. Further exploration 

 in other seas will probably prove that there are local faunae in the ar- 

 chibenthal areas, as there are on the shores, a conclusion which would 

 accord well with what we learn from paleontology. 



One point has been brought out by the study of the Blake collections 

 which was foreshadowed by Pourtales in his study of the deep-sea corals 

 dredged by him in the vicinity of the Florida reefs. It is being con- 

 firmed by present study of the mollusk fauna of our southern coast in 

 connection with the tertiary and quaternary fossils of the Atlantfc and 

 Gulf slopes. It is that a large proportion of the tertiary shells which 

 have been called Pliocene, or even Miocene, in this country and in 

 Sicily, still exist in a living condition near our shores. The tertiaries of 

 Calabria and of localities in the South of Italy having been pretty fully 

 studied, Pourtales was able to identify many of his corals with those 

 found by Italian paleontologists. Had our own tertiaries been half as 

 well known, or had he had a good collection of the shells of the southern 

 and West Indian tertiaries, he would have been able to recognize their 

 relations with his dredgings as being equally close. At least this is the 

 case with the molluscan fauna, if not with other invertebrate groups. 

 His dredgings, it should be clearly understood, were in the archibenthal, 

 and not the abyssal region, which last his operations never reached. 

 There is not enough known, so far, of the strictly abyssal mollusk 

 fauna, to afford a safe basis for generalization in connection with these 

 tertiaries. I may observe, however, that from middle Louisiana, ou 

 the edge of the Eocene beds, I have recently received certain fossils 

 which present every appearance of being a deep-water (archibenthal 1) 

 deposit, including Limopsis and several other characteristic forms. The 

 data which have been received relating to the circumstances under 

 which the fossils are found are as yet insufficient for a satisfactory 

 discussion of the subject. 



