288 A. E. Verrill— Mollusca 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; Tsenioglossa, 1; 
Ptenoglossa, 1; Nudibranchiata, 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, ete., 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 Rissoa, Cingula, 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 Litéopa, 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 southern genera, Doliwm, Marginella, Solarium, Avicula, 
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, 
