CRUSTACEA CASPIA. 447 



The body, especktlly iu the female (fig. 15), is exceedingly short aud 

 stout, with tlie back generally much curved. In male specimens it ap- 

 pears somewhat more slender, though still rather robust. The anterior half 

 of the body is perfectly smootli, without any trace of a dorsal crest. Tlie 

 posterior lialf, on the other hand, comprising the last 2 segments of the 

 mesosome aud those of the metasome, is very distinctly crested, each of the 

 segments being produced dorsally to a very prominent lamellar e.xpansiou. 

 The 4 anterior expansions are triangularly pointed, whereas the 5th, as iu 

 A. cristata, is rounded, gibbous. 



The ui'osorae is very short and stout, and witliout any dorsal pro- 

 minences, being only clothed with small hairs. 



The cephalon appears comparatively larger than in the otlier sjjecies, 

 considerably exceeding in length the first 2 segments of the mesosome com- 

 bined. In shape however, it, agrees with tliat in the other species, and has 

 the lateral lobes bluntly truncated. 



The anterior pairs of coxal jjlates are comparatively small, and have 

 the distal edge nearly smooth. The 1st pair are scarcely at all expanded 

 distally, and are about same breadth as the 2 succeeding ones. The 4th pair 

 exhibit a form similar to that in the preceding species. 



The epimeral plates of the metasome are of moderate size, and tlie 2 

 posterior pairs nearly rectangular. 



Tlie eyes are oval rouiform, having a slight sinus anteriorly. 



Tiie superior antennre are very slender and elongated, exceeding in 

 length even % of the body, aud having the 1st joint of the peduncle rather 

 large, being almost as long as the other 2 combined. The flagellum is fully 

 twice as long as the peduncle, and is composed of about 16 articulations. 

 The accessory appendage is rather small, aud composed, in the female 

 (fig. 16) of only 2, in the male (fig. 17) of 3 articulations. 



The inferior antennae are about half the length of the superior, and of 

 the usual structure. 



The gnathopoda iu the female are somewhat more unequal than iu the 

 other species, the anterior ones (fig. 18) being considerably more strongly 

 built than the posterior (fig. 19), though less elongated. The propodos of 

 the former (fig. 18) is rather broad, oval in form, and has the palm some- 

 what oblique; that of the latter (fig. 19) is unusually narrow, oblong linear, 

 with the palm very short and almost transverse. In the male, the gnatho- 

 poda (figs. 26, 27) are, as usual, very powerfully developed and nearly 

 equal-sized, the propodos being iu both pairs large and tumefied. 



The pereiopoda (figs. 20 — 23) are rather strongly built, and compara- 

 tively more elongated than in A. Maximowkzi. Their outer part is edged 



•^U3.-MuT. CTp. 377. 27 



