462 0. 0. SARS, 



carries a few fascicles of short bristles, whereas the opposite edge is quite 

 smootli. The dactylus is very long and falciform, its tip being received be- 

 tween the spines of the lower corner, when the dactylus is bent in against 

 the propodos. 



The pereiopoda are rather slender, and exhibit on the whole a normal 

 structure. The 2ud pair are somewhat more densely setiferous than the 1st, 

 but otherwise of the very same appearance. The basal joint of the last pair 

 is much larger than that of the 2 preceding pairs, and of oblong oval form, 

 with the posterior edge slightly curved and densely fringed with delicate setaj. 



The last pair of uropoda (see fig. 17) are not particularly elongated, 

 though reaching considerably beyond the others, and have the outer ramus 

 rather broad, sub-foliaceous, with a very small terminal joint. It is densely 

 fringed with slender seta3, and has, moreover, on the outer edge, 2 distant 

 spines The inner ramus is somewhat less rudimentary than in most other 

 species, being nearly '4 as long as the outer, and carries at the tip 2 small 

 spines. 



The telson (ibid.) is about as long as it is broad, and scarcely narrowed 

 distally. The cleft does not extend quite to the base, and it gradually widens 

 posteriorly. The lateral lobes are bluntly pointed, and carry each 3 lather 

 small and closely-set apical spines. 



Occurrence. — The above-described specimen was taken by Mr. War- 

 pachowsky at Stat. 59, lying at some distance outside the mouth of the 

 Wolga. 



18. Gammarus Weidemanni, G. 0. Sars, n. sp. 



(V). 9, figs. 1 — 11). 



Specific Characters. — Body comparatively robust and quite smooth, 

 witli broadly vaulted back. Lateral lobes of cephalon but slightly prominent, 

 and obliquely rounded. Anterior pairs of coxal jilates rather large, and 

 densely setiferous; 1st pair distinctly expanded in their outer part, 4th pair 

 very broad, with the posterior expansion transversely truncated. Last pair 

 of epimeral plates of metasome. but slightly produced at the lateral corners. 

 Urosome quite smooth above. Eyes of moderate size, oval reniform. Antennae 

 short, equal-sized, the superior ones with the flagellum longer than the pod- 

 uncle, accessory appendage 5-articulate. Inferior antennae with the 2 outer 

 joints of tlic peduncle simple, cylindric, clothed with scattered fascicles of 

 bristles. Mandibular palps of normal size. Gnathopoda in female comi)ara- 

 tively strong, and somewhat unequal, the posterior ones being the larger; 

 those in male, as usual, still more powerful. The 2 anterior pairs of pereio- 

 poda very robust, with the raeral and carpal joints lamellarly expanded and 



•I'll.i.-M.iT. CTj). 21)2. 42 



