BARBADOS-ANTIGUA EXPEDITION 91 
We found the deeper water just offshore much richer in species. 
An intermediate zone of from 5 or 6 to 30 or 40 fathoms is the 
dwelling place of numerous forms including some of these found 
dead on the shore, but the bottom is of so rough a character that 
no satisfactory work could be done with the dredge. Below 40 
fathoms patches of coarse sand appear between rocky areas. 
These smooth places seemed almost devoid of life, but often 
yielded the dead ‘‘bones’’ of the rock-dwelling mollusks. At 60 
to 70 fathoms the sand patches are more continuous and of finer 
grain, the rocky areas becoming less; at 100 fathoms the sand 
is very fine, almost soft and the rocks have quite disappeared. 
Thence to 120 or 150 fathoms narrow streaks of gravelly bot- 
tom are met and the sandy floor becomes quite soft. At about 
50 to 70 fathoms the character of the molluscan residents under- 
goes a very decided though not wholly abrupt change. The 
littoral and sub-littoral species, Strombus, Fasciolaria, the large 
murices, Oliva, the cypreas, tritoniums, the littoral colum- 
bellas and marginellas, ete. all disappear and are replaced by 
the Archibenthal zone forms. These are the turrids (Pleur- 
otomids) the scales, the smaller murices, cones, the deeper 
water species of Marginella, Columbella, Nassa, Mitra, ete. and 
the host of smaller mollusks making up the families of the py- 
ramidellids, the triforids, the cerithiopsids, the rissoids, trochids, 
ete. The dentalia and caduli gradually increase and the bot- 
tom becomes covered with the dead shells of pelagic pteropods. 
It was from 70 to 120 fathoms that we made our best hauls for 
mollusks and doubtless could we have reached 200 fathoms we 
should have found even better collecting. 
The soft sand bottom at about 100 fathoms we ealled the 
‘““Cerithiopsis ground’’ on account of the vast quantity of C. 
erystallina Dall it contained. 
Our knowledge of the mollusks from Barbados and the Lesser 
Antilles, excepting of the purely littoral forms is yet quite im- 
perfect. Krom Barbados we have the results of a few hauls 
made by the U. S. Coast Survey Steamer ‘‘Hassler’’ in 1872 
off ‘‘Sandy Bay’’ in 75 to 100 fathoms, and a few more by the 
Fish Commission Steamer ‘‘Blake’’, in 1879 in 6 to 400 fathoms. 
This material, a small collection at best, is in the U. S. National 
Museum and the Harvard Museum. 
