LYSIANASSA LONGICORNIS. 87 



Believing that the inferior antennae are organs adapted 

 for the sense of smell, we may conjecture that these 

 membranous attachments have the power of increasing 

 that faculty to a more acute degree. The fact of their 

 being found in the males only would seem to corrobo- 

 rate this supposition, since undoubtedly the males seek 

 the other sex by the use of this sense, as the following 

 experiment appears to demonstrate. Having separated 

 a male amphipod from a female, which he was carry- 

 ing about with his legs, the latter immediately swam 

 to a place of security, but the male dashed eagerly 

 round the trough in which they were confined. While 

 swimming about, however, we observed that, having 

 passed by his mate, he would turn back, and select her 

 from among several others. We think that this could 

 only have been performed by the agency of smell, and 

 therefore consider these calceola as organisms, connected 

 with and increasing the capability of that sense in the 

 male amphipods where they exist. 



The epistoma projects in a narrow perpendicular wedge- 

 like process, with a rounded apex, over which the in- 

 ferior antennae bend. 



The mandibles do not materially differ from those of 

 species of this genus previously described. The foot- 

 jaws have the fifth joint very long, nearly three times as 

 long as the sixth, and have squamous plates attached to 

 the third and fourth joints ; the plate belonging to the 

 fourth joint has the outer margin minutely waved, and 

 furnished with a submarginal row of minute cilia, that of 

 the third joint reaches to half the length of the fourth, 

 and is furnished towards the distal extremity with a 

 thick brush of cilia. The first pair of legs are short and 

 tolerably robust ; the wrist is about half the length of 

 the hand and stouter ; the hand from its articulation with 



