r 







\ 



VERTICAL RANGE OF DEEP-SEA SWIMMING FORMS. 



249 



») 



off 



ing from 500 to 570 fatlioms, where the soundings indicated a depth of 622 

 fathoms. A red, deep-sea Peneid, belonging to the genus Gennadas was 



found in the lower, closed part of the net.* 



There can be no doubt that the deep-sea natatory Crustacea occasionally 

 come to, or very near to, the surface. The first known specimen of Ilymeno- 

 dora gladalis, a species whose rudimentary eyes and whose structure ponit to 

 the depths as its nornuil dwelling-place, was taken at the surface, off the east 

 coast of Greenland. An immature specimen of Acantliephjra ag assizii w.is^ 

 caught at the surface, in a dip-net, during the cruise of the " Albatross 

 the east coast of the United States in 1884. This specimen was kept alive 

 for half an hour before it was put into alcohol. f A female of the nearly 

 related, if not identical, species, A. purpurea, was captured during the 

 " National " Expedition, swimming at a depth of less than 200 fathoms. 

 Spence Bate records a specimen of Gennadas secured at the surface on 

 the voyage of the " Challenger." Amalopencus, a genus identical with, or 

 at any rate most closely allied to, Gennadas, was found during the " Na- 

 tional " Expedition at a depth of less than 200 fathoms. Yet the same 

 thing was captured in the closing-net between 500 and 570 fathoms (bottom 

 622 fathoms) during the " Albatross " Expedition of 1891, and between 650 

 and 750 fathoms during the " National " Expedition. The genus Eucopia was 



first made known to science through a specimen recovered from the stomach 

 of a penguin killed in the Antarctic Sea. This specimen was presumably 

 captured by the bird in comparatively shallow water. According to Mr. 

 Agassiz's notes made on board the "Albatross," the same Schizopod was 

 captured in the open part of the Tanner tow-net between the surface and 

 300 fathoms at Station 3414 (2432 fathoms). Another individual, as we 

 have seen above, was taken in the closed portion of the net at a depth ot 



1000 fathoms. 



Spence Bate suggested that some of the free-swimming Crustacea of 



^. 



the deep sea may approach the surface to spawn 



a phmsiblc theory if 



one bears in mind the sensitiveness of young animals to cokh As the bot- 

 tom Crustacea of the deep sea may be supposed, from their structure and 

 affinities, to have originated directly from littoral ancestors, so the deep-sea 

 swimming forms have probably come from pelagic or surface species. 



* At Challongor Exped. Station 207 (2700 fatlioms), in tlie mid Nortli Pacific, a specimen of Gennadas 

 was captured in tlic open tou-net winch liad only been lowered to within 700 fathoms of the bottom. 

 t See S. 1. Smith, in Ann. Rep. U. S. Fisli Comm. for 1SS5, p. GG7, 18S6, 



32 



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