62 THREE CRUISES OF THE “BLAKE.” 
by the Fish Commission off Martha's Vineyard from a depth 
of over 1,000 fathoms. 
The giant squids (Fig. 281) of the North Atlantic (Architeu- 
this), occasionally thrown up on the shores of Newfoundland, 
attain an immense size, the arms measuring fully forty feet in 
length. They probably live in the regions where food is most 
abundant, upon the slopes, near the boundary of the continen- 
tal plateau. It will be some time before we are able, with our 
present appliances, to capture such monsters from the depths at 
which they live. The Belemnites, so characteristic of some of 
the tertiary deposits, have not as yet been dredged. 
GASTEROPODS AND LAMELLIBRANCHS.' 
The Mollusca obtained by the * Blake” are notable in several 
respects. We may refer to the absence or rarity of very minute 
forms, which are only accidentally preserved in the contents of a 
trawl net, even from comparatively shallow water. It is hardly 
to be expected that, in the long washing which the contents of 
a trawl undergo while hauled in from deep water, anything small 
enough to go through the finest meshes of the bottom net 
should be retained. Yet large shells appear to be rare in the 
great depths, and are usually so fragile that their destruction or 
fracture is almost inevitable. Deep-sea dredging has thus af- 
forded few specimens of even moderately large size, judged by 
the standard of shallow-water or littoral shells. Among naked 
mollusks several species of unusual size have been found by dif- 
ferent expeditions. One as large as an orange, discovered by 
the “Challenger,” was named by Dr. Bergh Bathydoris abys- 
sorum. It is perhaps the largest nudibranch known; it has a 
transparent and gelatinous consistency, and with neither eyes 
nor otocysts it must-have led a remarkably sluggish existence, 
blind and deaf as it was. 
Abyssal mollusks are probably less active and energetic than 
their congeners of the shores. This is indicated by the loose- 
ness of the tissues, less favorable to prompt and violent action 
than a more compact muscular system would be. The tena- 
1 Mr. Dall has kindly prepared for me mellibranehs, and supervised the drawing 
the account of the Gasteropods and La- of the figures. 
