528 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [26] 



the " Fish Hawk " and "Albatross," off our northern coast, exclusive of 

 those dredged only in shallow water, included 380 species and 21 named 

 varieties. But of these, at least 42 are pelagic species, taken either 

 alive at the surface or dead at the bottom, viz : Cephalopoda, 2 ; Tgenio- 

 glossa, 1; Ptenoglossa, 1; Nudibranchiata, 4 (2 live also in shallow 

 water); Heteropoda, 8; Pteropoda, 24 ; Lamellibranchiata, 3 (2 live also 

 in shallow water). Possibly a few other species, now considered as 

 deep-water forms, may be pelagic, for it is difficult to tell at what depths 

 free-swimming species of Cephalopods are taken, unless they occur in 

 the stomachs of the deep-sea fishes. Many small Gastropods, &c., 

 living habitually on floating Fucus and Sargassum, are caught with 

 these sea- weeds in the trawl, on its way up or down, and mingling with 

 the shells from the bottom may give rise to errors of this kind. Thus 

 some of the species of Bissoa, Gingula, Cithna^ &c., may not really live 

 at the depths recorded, but at the surface. There were also a consid- 

 erable number of minute, undetermined species not included in the list. 

 During the season of 1884 about 40 species, of which about 25 were 

 undescribed, were added to this list. These are largely from the deepest 

 dredgings. 



Of the 343 species* and 20 named varieties in my published list 

 of 1883, regarded as living at the bottom, 89 are also shallow-water 

 forms, living habitually in less than 60 fathoms, in this region. A con- 

 siderable number, considered as deep-water species on this part of the 

 coast, occur in shallow water north of Cape Cod, and some of them may 

 eventually be found to occur in the cold belt off Martha's Vineyard in 

 25 to 60 fathoms. Of the shallow-water species, 63 occur also between 

 200 and 500 fathoms, and 18 below 1,000 fathoms. Some of these have 

 a remarkable great range geographically, as well as in depth. Of the 

 273 species and varieties regarded as belonging to the deep-water fauna 

 in this region, 143 have occurred in the comparatively warm zone, be- 

 tween 60 and 200 fathoms. A considerable number of these have been 

 taken only in the more southern dredgings, off Chesapeake Bay and 

 Cape Hatteras, and some of them only in depths not much exceeding 

 100 fathoms, where the Gulf Stream has the greatest effect. In this 

 zone occur species belonging to southern genera, such as Dolium 

 Bairdii (fig. 83), Marginella borealis (fig. 79), Solarium boreale (figs. 95, 

 95«), Avicula hirundo, &c. 



The number that occupy the zone between 200 and 500 fathoms is 128, 

 while 118 inhabit the depths between 500 and 1,000 fathoms, and 96 

 have been taken between 1,000 and 2,000 fathoms. Although but five 

 of our dredgings have been in more than 2,000 fathoms,t we are able to 



* More recent studies of the 1883 shells have added several species to the list, mostly 

 from the deeper localities. They are included in the accompanying list. 



t During the season of 1884 other series of dredgings were made in the same region 

 in depths below 2,000 fathoms. From these a large number of additional species of 

 MoUusca and other groups were obtained. 



