288 A. E. Verrill — 3foUusca of the New England Coast. 



In the above list are 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 ; Taenioglossa, 1 ; 

 Ptenoglossa, 1 ; Nudibranehiata, 4 ; Heteropoda, 8 ; Pteropoda, 23 ; 

 Lamellibranchiata, 3, 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 

 also occur in the stomachs of deep sea fishes. Many small Gastro- 

 pods, etc., living habitually on floating Eucus and Sargassimi^ 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 Hissoa, Cingiila, Cithna^ 

 etc., may not really live at the depths recorded, but at the surface. 

 When satisfied of this accidental occurrence of some of the common 

 shore species (Littorina, etc.), I have omitted them from the list, but 

 have included the strictly pelagic forms, like Litiopa, for convenience. 



Of the 343 species and 19 named varieties regarded as living at the 

 bottom, 89 are also shallow- water species, living habitually in less than 

 60 fathoms, on this part of the coast. A considerable number, now 

 considered as deep-water species in this region, 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 89 shallow-water species, 63 occur also between 200 and 500 

 fathoms, and 19 below 1000 fathoms. Some of these have a remark, 

 ably great range geographically, as well as in depth. 



Of the 259 species and 14 varieties regarded as belonging to the deep- 

 water fauna, in this region, 143 occur in the comparatively warm zone, 

 between 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 exceed- 

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

 zone the soiitliern genera, DoUiwi, 3Iarghiella, Solarium., Avicitla, 

 etc. occur. The number that occupy the zone between 200 and 500 

 fathoms is 128, besides 63 shallow-water species, while 118 inhabit 

 the depths between 500 and 1000 fathoms, associated with 30 shallow- 

 water forms, and 96 have been taken between 1000 and 2000 fathoms, 

 associated with 19 shallow- water ones. Although but five of our 

 dredgings have been in more than 2000 fathoms, we are able to 

 record 35 species from between 2000 and 3000 fathoms, which is a 

 much greater number than has hitherto been recorded from such 

 depths in the north Atlantic. 



