CRUSTACEA CASPIA. 189 



Avith a series of flattened spines increasing in size towards tiie tip, where 

 they successively become transformed to strong curved set£e. The palp is 

 "«^ell developed, suljpediform, and composed of the usual 3 joints, the outer 

 2 of which form together a more or less pronounced geniculate bend. The 

 last joint is somewhat expanded in its outer part, which is densely setous, 

 and carries at the tip a claw-like movable spine (the dactylus). 



The gnathopoda {figs. 15 and 16) are comparatively small and most 

 frequently so closely applied against the buccal area, as to be quite hidden 

 between the 2 anterior pairs of coxal plates, to the inner face of which they 

 are articulated. They are nearly alike both in size and structure, both pairs 

 being densely setous and exhibiting a more or less pronounced sigmoid 

 curve. The basal joint is somewhat more elongated in the posterior ones 

 (fig. 16) than in the anterior, whereas the 3 succeeding joints are exactly 

 alike in both pairs, the carpus being about the length of the 2 preceding 

 joints combined and forming below a slight setous expansion. The propodos 

 is about as long as the carpus and scarcely broader, exhibiting in both pairs 

 a distinct subcheliform structure. Its shape is a little different in the 2 pairs, 

 the palm being in the anterior ones (fig. 15) somewhat oblique, whereas in 

 the posterior ones (fig. 1 6) it is nearly transverse. The dactylus is not very 

 strong and of the length of the palm. 



The pereiopoda (see fig. 1, comp. also PI. II, figs. 4 — 7) are rather 

 much elongated and but little different in length, all being fringed on both 

 edges with numerous fascicles of short bristles, and having the dactylus 

 rather slender. The 2 anterior pairs are, as usual, generally turned anteri- 

 orly, whereas the 3 posterior pairs are more or less strongly reflexed; in 

 the former the basal joint is comparatively imrrow, in the latter more 

 lamellar in character. Of the several joints composing these limbs, the basal 

 one is in all much the largest and the ischial joint the shortest, the 3 suc- 

 ceeding ones being nearly of equal length. The antepenultimate and pen- 

 ultimate pairs are somewhat longer than the others, and have the basal 

 joint but little expanded and gradually tapering distally. The last pair 

 (comp. PI. II, fig. 7) are a little shorter than the 2 preceding pairs, and 

 differ considerably in the form of the basal joint, which is much broader 

 and considerably expanded in its distal part, the posterior edge being 

 strongly curved below the middle and fringed throughout with short 

 bristles. 



The branchial lamellae, present at the base of all the legs, except the 

 anterior gnathopoda, are well developed, though, as usual, considerably 

 diminishing in size posteriorly. The anterior pairs (see PI. I, fig. 1 6) are 

 rather large and broad, subtriangular in form, and attached by a short but 



4»H3.-MaT. CTp. 189. 11 



