156 A New Species of Apus. 



served before, it is impossible to determine where it should bo 



arranged. 



* APUS LONGIOAUDATUS. 

 Pale brown : buckler large, thin, gibbous, nearly round, carinate 



on the middle of the back, deeply emarginate behind, the edges of 

 the emargination fringed with short spines: eyes three, simple, the 

 two anterior larger, approximate, somewhat lunate, the third one 

 round, placed in the middle behind the two others : antennae very 

 short, inserted near the mandibles, two-jointed, joints clyndrical, 

 subequal, the second joints somewhat accumulate and naked at the 

 tip : first pair of feet, or as they have been called, exterior anten- 

 nae, furnished with four articulated filaments; of these filaments, 

 the outer one is longer than the body, the next half the length of 

 the first, the third about one third the length of the second, and 

 the fourth very short : the other feet, amounting to ten pair, are 

 flattened, trifid at the tip, the intermediate division being the long- 

 est, furnished ou the inner side with a short branch, and exter- 

 nally with a broad lamina : below these feet arc twelve pair of 

 lamin-.e. the live anterior pair larger, the seven smaller pair reach- 

 ing to the vent, which is covered by the last pair ; these laminae 

 are complicated in their structure, and ciliate with short hairs: 

 tail long, consisting of sixteen joints counting downwards from 

 the vent, the last one the longest, somewhat coriaceous, emargi- 

 nate and ending in two long articulated naked filaments, the joints 

 of the tail and of* the filaments are furnished each with a row of 

 small spines, which run entirely round. 



Length to the end of the tail, 1.5 of an inch, of the buckler, 

 .05, breadth of the same, 7. 



■Male HI., fig. I. (a.) one of the feet, (b.) one of the lamina 1 . 



Of the habits of this animal, we know but little; it was found 



in immense numbers in a small shallow lake on the high plateau 



between Lodge-pole creet and Crow creek, north-east of Lon 

 peak: they were swimming about with great activity, plunging to 

 the bottom and r ing in the surface. All of them that wi re cauj 

 appear to be male . at l< ai I none of them have any ova attached : 



th( aon in Europe, A. cancril lis, on the contrary, 



never been found but of the opposite s< s. 



