CRUSTACEA CASPIA. 187 



curring about in the middle, whence the body gradually tapers both ante- 

 riorly and posteriorly. The lateral spines become, in this view of the 

 animal, very conspicuous, projecting, as they do, from each side of the meso- 

 some. The extent between tlie tips of tlie large mucroniform processes of 

 the 5th segment considerably exceeds half the length of the whole body. 



The eyes (see figs. 1 and 2) are placed on the lateral faces of the 

 cephalon, at some distance from the anterior edge and somewhat nearer the 

 dorsal than the ventral side. They are comparatively small and of rounded 

 form, with very dark pigment. 



The superior antennae (fig. 3) somewhat exceed in length Vg of the body 

 and are rather slender, being densely supplied with delicate bristles on both 

 edges.*" They are very flexible and generally so much recurved, as to be 

 nearly completely hidden between the lateral processes of the head and the 

 coxal plates. Of the 3 joints of the peduncle the 1st is much the largest, 

 equalling in length the other 2 combined and being much thicker. The last 

 2 joints of the peduncle are nearly of equal length, but the last is somewhat 

 narrower than the 2nd. 



The flagellum is nearly twice as long as the peduncle, and composed of 

 numerous short setiferous articulations, their number amounting to al)out 

 25 in all. The accessory appendage seems at the first sight to be entirely 

 wanting. On a closer examination, however, an extremely small nodule is 

 found in the place, where in other Gammaridse this appendage occurs. This 

 nodule is distinctly defined from the last peduncular joint, and carries on 

 the tip 2 delicate bristles. 



The inferior antennae (fig. 4) are much shorter than the superior, but 

 little exceeding half their length, and, as the latter, are rather densely 

 setiferous and generally strongly recurved. In every case their basal part 

 remains quite hidden by the lateral processes of the head, and can only be 

 examined by dissection. They are on the whole quite normally constructed, 

 exhibiting a comparatively large globular basal joint, followed by a very 

 short joint, from which inside the olfactory spine issues. The 3rd joint is 

 likewise rather short but comparatively thick, whereas the 2 remaining 

 joints of the peduncle are much more elongated, the penultimate one being 

 the larger. The flagellum is about same length as the last 2 peduncular 

 joints combined, and composed of 9 articulations. 



The buccal area is not very much prominent, and scarcely visible in a 

 lateral view of the animal, it being almost completely hidden between the 

 1st pair of coxal plates. The several oral parts composing it, are on the 

 whole of a quite normal structure, agreeing with that generally found in 

 the typical Gammaridae. 



■fHa.-MaT. cip. 187. 9 



