(XXXVI) | CRUSTACEA CASPIA. 307 
Its inner edge is minutely serrulate, and has 2 small spinules, the 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 the terminal joint is very narrow and conically tapering. 
It terminates in a very slender and elongated spine, and has the inner edge 
minutely serrulate, and provided near the tip with a single small seta. 
The 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. 
Description of the male. 
(Pl. 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 81, mm. 
The form of the body (see figs 1 and 2) is, on the whole, much more 
slender than 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 much narrower, and haye the epimera more expanded 
laterally. Those of the last segment terminate in an obtuse projection fringed 
with several plumose setze. 
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 
cornez very distinct and highly refractive. 
The superior antennæ (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 5 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 antennæ (fig. 5), differing in this respect from the female, are 
greatly developed, attaining nearly the length of the whole body. They con- 
Mélanges biologiques. T. XIII, p. 471. 21 
