T. XIIl] CRUSTACEA CASPIA. 475 



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 

 1st 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 cylinclric, without any 

 dorsal keels. 



The antennas (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 



Bulletin N. S. IV (XXXVI) p. 311. 



