(XXXVI) J CRUSTACEA CASPIA. 307 



Its inner edge is minutely serrulate, and has 2 small sjjinules, tlic one about 

 in the middle, the other close to the apex. The outer ramus is a little shorter 

 than the inner, and distinctly biarticulate, with the basal joint rather short 

 and thick, whereas tiie terminal joint is very narrow and conically tapering. 

 It terminates in a very slender and elongated spine, and has the innei- edge 

 minutely serrulate, and provided near tiie tip with a single small seta. 



Tlie telson (see fig. 18) is very small, and of a quadrangular form, some- 

 what broader than it is long, and without any armature whatever. It is 

 distinctly defined from the last segment, and to a certain extent mobile, 

 allowing of being bent down between the uropoda, thus covering over the 

 anal orifice. 



Desrripliun ol' the male. 



(PI. II). 



Adult male specimens differ rather markedly from the females, both in 

 the outer habitus, and in several of the anatomical details. They also attain 

 a somewhat larger size, the length of the body measuring about S'A mm. 



The form of the body (see figs 1 and 2) is, on tlie whole, much more 

 slender tlian in the female, and the anterior division is far less tumid, and, 

 as seen from above (fig. 1), nearly of equal breadth throughout. 



The carapace has the branchial regions considerably swollen, though 

 scarcely gibbous posteriorly, as in the female. The pseudo-rostral projection 

 is shorter and more obtuse at the tip, and the antero-lateral corners broader 

 and more expanded laterally. 



The free segments of the mesosome are armed in a similar manner to those 

 in the female, but are mucli narrower, and have the epimera more expanded 

 laterally. Those of the last segment terminate in an obtuse projection fringed 

 with several plumose setae. 



The metasome is somewhat more strongly developed, and exceeds the 

 anterior division in length. 



The eye (fig. 3) is considerably larger than in the female, and has the 

 corner very distinct and highly refractive. 



Tlie superior antenna3 (fig. 4) do not differ from those in the female, 

 except in the flagella being divided into a greater number of articulations. 

 The outer flagellum consists of,') well-defined joints, the 1st of which is 

 rather short. The inner flagellum is less rudimentary than in the female, 

 attaining nearly half the length of the outer, and is composed of 2 distinct 

 joints. 



The inferior antennte (fig. 5), differing in this respect from the female, are 

 greatly developed, attaining nearly the length of the whole body. They con- 



JlclllllgCS ViiologiqiW.t. T. Xjn, p. ITI. 01 



