rRUSTACEA CASPIA. 423 



joint about the length of the remaining part of the leg, oval, broadest in 

 its upper part, infero-posteal corner produced to a rounded lobe, posterior 

 edge divided into -about 7 serrations. Last pair of uropoda with both rami 

 simple mucrouate. Telson with the tip slightly notched on each side and 

 obtusely produced in the middle. Length 9 mm. 



Remarks. — The present form, detected by Dr. Grimm, is unquestion- 

 ably congeneric with the arctic species, P. littoralis, though easily dis- 

 tinguishable by the less elongated antennae, and the somewhat different 

 structure of the gnathopoda. Also the pereiopoda, uropoda and telson ex- 

 hibit some points of difference. One specimen in the collection of Dr. Grimm, \ 

 named Onesimus pomposus, I regard as only a young male of the present 

 species. 



Description. — The length of an apparently adult female specimen ^ 



measures about 9 mm., and this form is accordingly somewhat inferior in 

 size to the arctic species. 



The general form of the body (see fig. 1) resembles that of the said 

 species, though being perhaps somewhat shorter and stouter, with the back 

 generally much curved and, as in most other Lysianassidae, quite smooth. 



The cephalon (fig. 4) somewhat exceeds in length the 1st segment of 

 the mesosome, and has the lateral lobes slightly produced, and narrowly 

 rounded at the tip. The postanteunal corners are distinct and nearly rect- 

 angular, and behind them there is on each side an angular incision, into 

 which the upper end of the mandible is received, the incision being defined 

 behind by an acute lappet. 



The anterior pairs of coxal plates are somewhat deeper than the cor- 

 responding segments, and densely crowded. The 1st pair (see fig. 11) are 

 considerably broader than the others, and widen somewhat distally, with 

 the end obtusely truncated and provided at the posterior corner with a 

 small dentiform projection. The 2 succeeding pairs (see fig. 1 3) are remark- 

 ably narrow, the 4th pair (see fig. 14) also being of inconsiderable breadth as 

 compared with most other LysianassidsB. 



The 3 posterior pairs of coxal plates exhibit the usual shape, the ante- 

 penultimate pair (see fig. 15) being rather broad, of a rounded quadrangu- 

 lar form. 



The epimeral plates of the metasome are well developed, the 1st pair 

 being, as usual, rounded, whereas the other 2, and especially the last one, 

 are rather acutely produced at the lateral corners. 



The urosome is quite smooth, and has the 1st segment very slightly de- 

 pressed above, in front of the middle. 



*H3.-MaT. CTp. 253. J 29* 



