(xxxv1] CRUSTACEA CASPIA. 311 
responding far more with that of the adult male of the latter species. The 
anterior division is, however, as in most female Cumacea, rather tumid, and, 
as seen from above (fig. 1), of oblong ovoid form, with the greatest breadth 
about in the middle, and gradually tapering both anteriorly and posteriorly. 
The carapace about equals in length the exposed part of the trunk and the 
lst segment of metasome combined. It is, as seen laterally (fig. 2), of an ir- 
regular oval form, and somewhat truncated in front. The branchial regions 
are considerably swollen and evenly rounded above, with a low crest run- 
ning along their most prominent part. These crests are coarsely serrated, 
and are continued anteriorly, on each side of the gastric region, as an hori- 
zontal ridge until the tip of the pseudo-rostral projection. The latter is very 
short and obtusely truncated at the tip, whereas the antero-lateral corners 
of the carapace are greatly projected, forming broad triangular lappets, the 
anterior edge of which is very coarsely serrated (see fig. 3). The gastric 
region (see fig. 1) exhibits the usual bell-shaped form, and has along the 
middle a slight, minutely serrated keel. The ocular lobe is of a rounded 
triangular form, and has the visual elements but slightly distinct, the median 
cornea even being quite inconspicuous, The inferior edges of the carapace 
have their greatest curvature about in the middle, and, as in the preceding 
species, join the posterior edge, without forming any angle. 
The free segments of the mesosome are sharply defined from each other, 
and all distinctly keeled dorsally. On the 3 anterior segments the keel is 
elevated to comparatively small, rounded projections, finely serrated on the 
edge; on the 2 posterior segments the projections are somewhat larger and 
laminar, though not nearly so prominent as in the preceding species; 
that of the last segment is the largest and of triangular form, with the an- 
terior edge, as in the preceding one, coarsely serrate. Of the rounded jux- 
taposed dorsal prominences occurring in P. pectinata on the 2nd segment, 
no trace is to be found. The epimera are rather broad, and of a similar form 
to those in that species. 
The metasome is rather strongly built, and considerably longer than the 
anterior division of the body. Its segments are simple cylindric, without any 
dorsal keels. 
The antennæ (fig. 4) and oral parts do not differ materially from those 
parts in the preceding species. 
In fig. 5 the left branchial apparatus is represented in its natural con- 
nexion with the corresponding maxilliped. As will be seen, it consists of 2 
principal parts: a narrow band-like portion stretching anteriorly, and a 
broad navicular plate extended backwards. The former, representing the 
modified exopodite, expands at the end to a triangular, slightly incrusted 
Melanges biologiques. T. XIII, p. 475. 
