476 G. 0. SARS, [t. XIII 



lamella, which meets the corresponding lamella on the other side in front of 

 the pseudo-rostral projection, both forming together a valvular apparatus, 

 regulating by its movements the current of the water introduced into the 

 branchial cavity. The large, posteriorly-pointing plate, representing the epi- 

 podite, is somewhat hollowed, exhibiting a convex outer face and a slightly 

 concave inner cavity; it terminates with a narrow, triangular, recurved 

 lappet, and carries along the inner edge a series of 4 sacciform gill-elements, 

 rapidly decreasing in size posteriorly; another much larger gill-sac is seen 

 issuing from the inner face of the plate, somewhat in front of the others. 



The gnathopoda (figs. 6 and 7) exhibit a similar structure to those in the 

 preceding species. As the specimen selected for dissection was a young fe- 

 male, the marginal setse of the basal lamellae of the anterior gnathopoda are 

 only indicated as short projections (see fig. 6), and the incubatory plates of 

 the posterior ones are still small and of a triangular form (see fig. 7). 



The legs (figs 8 — 11) likewise are very similar in structure to those of 

 the preceding species, and it will thus be sufficient to refer to the figures, 

 without giving a detailed description. 



The uropoda (fig. 1 2), though constructed upon the same type as in the 

 said species, differ conspicuously in being comparatively much shorter and 

 stouter, scarcely exceeding in length the last 2 segments of the metasome 

 combined. The scape is rather thick, and has on the inner edge 8 small 

 bristles, the 3 anterior of which are separated from the others by a larger 

 interval. The rami are about the length of the scape, and nearly equal-sized. 

 They are both minutely ciliated along the inner edge, and terminate with a 

 strong, though not very elongated spine, close to which there is a small 

 bristle; but otherwise they are quite devoid of lateral spinules. 



The telson (fig. 13), as in P. pectinata, is transversely quadrangular in 

 form, being much broader than it is long. 



Colour. — Also of this form, some specimens recently received still ex- 

 hibited a number of reddish brown pigmentary patches, arranged both on 

 the anterior and posterior divisions of the body, and especially very con- 

 spicuous on the carapace. As seen from the figures (1 and 2), their number 

 was somewhat greater than in P. pectinata, and the ramifications less ex- 

 tended. 



Occurrence. — Of the present species I at first had for examination only 

 a few still immature specimens, which I found among the material of P. pec- 

 tinata, from Stations 2, 32, 48 and 50, all belonging to the western part 

 of the North Caspian Sea. In a collection recently received from Mr. "War- 

 pachowsky, however, a number of fully grown ovigerous females were 

 included. These specimens were derived from 4 different places, 2 of which 



Bulletin N. S. IV (XXXVI) p. 312. 



