170 THE VOYAGE OF H.M.S. CHALLENGER. 



species would appear to inhabit all depths from the surface downiwards. This is 

 extremely improbable, and its frequent capture is only a proof of its abundance in all 

 tropical seas, and of the slowness of its movements, which prevent it from getting out 

 of the way of the dredge or net. Like Argyropelecus it is a pelagic fish, which 

 probably lives in shoals, as sometimes more than one example were obtained in the same 

 haul. Possibly it may descend to or beyond the 100 fathoms line during the day-time. 



Messrs. Goode and Bean have included this species in their Report on the " Blake " 

 collection, from depths of 229 and 457 fathoms.^ 



Habitat. — Between Tencrife and St. Thomas ; surface. Two specimens, § and 1 

 inch long. 



Off Sierra Leone, Station 101 ; depth, 2500 fathoms. One specimen, ^ inch long. 



Mid Atlantic, Station lOG ; depth, 1850 fathoms. One specimen, If inches long. 



Mid Atlantic, Station 107 ; depth, 1500 fathoms. Two specimens, f and 1^ inches long. 



South of Australia, Station 159 ; depth, 2150 fathoms. One specimen, 1^ inches long. 



Kermadec Islands, Station 171 ; depth, 600 fathoms. Two specimens, 1^ and 2 

 inches long. 



Philijjpine Islands, Station 214; depth, 500 fathoms. Six specimens, 1|- and 1 

 inch long. 



North of New Guinea, Station 218; depth, 1075 fathoms. One specimen, 2 inches 

 long. 



South of Yedo, Station 235 ; depth, 565 fathoms. One specimen, 2 inches long. 



Polyipnus, n. gen. 



This genus differs from Sternoptyx in having the body covered with large, very thin 

 and deciduous scales, and in lacking the anterior spinous dilatation of the dorsal fin. 

 Habitat. — Philippine Islands. 



Polyipnus spinosus, n. sp. 



D. 12. A. 15. 



Occiput terminating in a pair of horizontal spines pointing backw^ards. 



Habitat. — Between the Philippine Islands and Borneo, Station 200; depth, 250 

 fathoms. One specimen, 2\ inches long. 



This fish differs from Sternoptyx in having the body of a more regular shape, there 

 being no deep indentation by which the tail is separated from the trunk. The form of 

 its outline is oval, its greatest depth being contained once and two-thirds in the total 



> Bull. Mm. Camp. Zool, vol. x., 1883, p. 220. 



