154 



SCIENCE. 



n'oi.. II., No. 27. 



greater thnn 200 fathoms on the outer slope, 

 and in 25 to 60 fathoms on the inshore plateau, 

 there is doubtless a slow, cold current to the 

 sonth-west. It is not probable that these 

 bottom-currents are strong enough to move 

 even the fine sand after it has once actually 

 reached the bottom ; nor is it strong enough 

 to prevent the general deposition of oceanic 

 foraminifera, pteropods, etc. 



The existence of actual currents in this 

 region, sufficiently' powerful to directly effect 

 an erosion of the bottom, is hardly supposable. 

 Such a result maj' be effected, however, in con- 

 sequence of the peculiar habits of certain fishes 

 and Crustacea that abound on these bottoms. 

 Many fishes, like the ' hake ' (Phycis) , of 

 which three species are common here, have the 

 habit of rooting in the mud for their food , which 

 consists largely of Annelida and other mud- 

 burrowing creatures. Other fishes, those with 

 sharp tails especially, burrow actively into the 

 mud or sand, tail first; and in all probabilitj' 

 Macrurus, abundant on these slopes, has this 

 habit. Several burrowing species of true eels 

 and eel-like fishes are very abundant on these 

 bottoms. Many of the crabs and other Crus- 

 tacea are active burrowers. Such creatures, 

 \>y continually stirring up the bottom sediments, 

 give the currents a chance to carry awaj' the 

 finer and lighter materials, leaving the coarser 

 .behind. 



, In man}' localities there are great quantities 

 of dead shells, both broken and entire. A 

 small proportion of the unbroken bivalves have 

 been drilled bj' carnivorous gastropods, but 

 there are large numbers that show no such 

 injury. These have, for the most part, un- 

 doubtedlj' served as food for the star-fishes and 

 large Actiniae, abundant on these grounds, 

 and from which I have often taken manj' kinds 

 of entire shells, including delicate pteropods. 

 Manj' fishes, like the cod, haddock, hake, 

 .flounders, etc., have the habit of swallowing 

 shells entire, and, after digesting the contents, 

 the}' disgorge the uninjured shells. Such fishes 

 abound here. Species of Octopus are also 

 known to feed upon bivalves without breaking 

 them, and O. Bairdii is common in these 

 depths. The broken shells have probabl}' been 

 ■destroyed, in large part, by the large crabs and 

 other crustaceans having claws strong enough 

 to crack the shells. The large species of Cancer 

 and Gerj'on, and the larger Paguri, abundant 

 in this region, have strength sufflcient to break 

 most of the bivalve shells. Many fishes that 

 feed on mollusca also crush the shells before 

 swallowing them. Both fishes and crabs have, 

 doubtless, thus helped to accumulate the broken 



shells that are oflen scattered abundantly over 

 the bottom, both in deep and shallow water. 

 Such accumulations of shells would soon become 

 far more extensive than they are, if they were 

 not attacked by boring sponges and annelids. 

 Certain common sponges, belonging to the 

 genus Cliona, very rapidly perforate the hard- 

 est shells in every direction, making irregular 

 galleries, and finally utterlj' destroying tliem. 

 On the outer grounds we dredge up rarely 

 fragments of wood ; but these are general!}' 

 perforated by the borings of bivalves (usually 

 Xylophaga dorsalis) and other creatures, and 

 by them would evidently soon be destroyed. 



We very rarely meet with the bones of 

 vertebrates at a distance from the coast. 

 Although these waters swarm with vast schools 

 of fishes, while sharks, and a large sea-porpoise, 

 or dolphin (Delphinus, sp.), often occur in 

 large numbers, we very rarely dredge up any 

 of their bones. In a few instances we have 

 dredged a single example of a shark's tooth, 

 and occasionally the harct otoliths of fishes. 

 It is certain that not merely the flesh, but most 

 of the bones also, of nearly all the vertebrates 

 that die in this region, are very speedily de- 

 voured by the various animals that swarm on 

 the bottom. Echini are very fond of fish- 

 bones, which they rapidly consume. Fishes 

 caught on the hooks in this region, and left 

 down an hour or two, were nearly stripped of 

 their flesh by small amphipod Crustacea. 



Relics of man and his works are of ex- 

 tremely rare occurrence at a distance from 

 the coast, or even at a short distance outside 

 of harbors, with the exception of the clinkers 

 and fragments of coal thrown overboard from 

 steamers with the ashes. As our drcdgings 

 are in the track of European steamers, such 

 materials are not rare. A few years ago, 

 even these would not have occurred. A rock 

 forming on this sea-bottom would, therefore, 

 not contain much evidence of the existence of 

 man, nor even of the commonest fishes and 

 cetaceans inhabiting the waters. 



5. Fossilif erous magnesian limestone nodules. 



At several localities in 234 to G40 fathoms, 

 we dredged fragments and nodular masses or 

 concretions of a peculiar calcareous rock, evi- 

 dently of deep-sea origin, and doubtless formed 

 at or near the places where it was obtained. 

 These specimens varied in size from a few 

 inches in diameter up to oue irregular nodular 

 or concretionary mass taken in G40 fathoms, 

 which was 29 inches long, 14 broad, and 6 

 thick, with all parts well rounded. These 

 masses differ much in appearance, color, tex- 



