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



exhibit a structure perfectly similar to that iu Lophogaster, the exopodite here also being 

 imperfectly developed, forming only a very small setous lamella {x). 



The first pair of legs (fig. 13), as in Lophoyaster, diflfer perceptibly from the 

 remaining pairs, being somewhat more robust in structure, and having the terminal 

 joint not unguiform, but of an oval shape, and densely beset with bristles. Hence this 

 pair may properly be regarded as true gnathopoda. 



The remaining legs (fig. 14) are all true pereiopoda, but have comparativel}' a more 

 feeble structure than in Lophogaster, with the carpal joint more elongate, whereas the 

 terminal one, or dactylus, is much shorter. 



The last pair of legs (fig. 15) are chiefly distinguished by the want of natatory 

 branches or exopods, in the place of which only a diminutive setous tubercle is to be seen. 

 This, however, may perhaps be a characteristic peculiar to the females. 



The caudal limbs (see fig. 8) are normally developed, and do not seem to difier essen- 

 tially in structure from those in Lophogaster. 



The telson (fig. 17) somewhat exceeds in length the two preceding segments taken 

 together, and exhibits a form similar to that iu Lophogaster, but difi'ers materially iu 

 the apex not being entire but deeply cleft, or produced into two acuminate and 

 diverging lappets, somewhat resembling the tail of a swallow. The inner edge of these 

 terminal lappets is indistinctly serrated. For the rest every trace of spines or bristles is 

 entirely wanting. 



The uropoda (fig. 17) are most unusually small, being scarcely half as long as the 

 telson, and with both their terminal plates of a uniform ajapearance, lanceolate, and setose 

 on Ijoth margins. 



ILah it at. —The solitary specimen descril)ed above I found in a small bottle containing 

 Euphausiidae, larvse of Macrura, and certain other pelagic animals, all of which, as shown 

 by the label, were collected at the surface of the sea iu the Pacific Ocean, between Api 

 (New Hebrides) and Cape York (Australia). 



This occurrence, certainly, is very remarkable, since none of the other Lophogastridse 

 are known to lead a pelagic existence. Indeed, judging from the organisation of the 

 present species, and more especially the very firm and highly indurated integuments, one 

 would indeed be induced to regard it as still more decidedly a bottom form than 

 most of the other Schizopods. 



Genus 3. Gnathophausia, Willemoes-Suhm, 187^. 



Gnathophmisia, Suhm, Trans. Linn. Soc. Loud., ser. 2, vol. i. \$*}S 



Generic Cliaracters. — Integuments generally not very firm, parchment-like. Carapace 

 rather large, in the greater part of its length only loosely covering the trunk, and 

 exteriorly provided with raised longitudinal keels. Rostrum more or less elongate and 



