CRUSTACEA CASPIA. 213 



similar to that in the northern species, G. campijlops Leacli. Tlie pigment 

 in most of the specimens is dark, but Dr. Grimm has stated a case of the 

 eyes being nearl^' devoid of pigment. 



The superior antennaj (see fig. 1 ) about equal half the length of the 

 body, and are very slender, with only scattered short hairs at the edges. 

 The joints of the peduncle rapidly diminish in size, the 1st being much the 

 largest and about equalling in length the other 2 combined. The last ped- 

 uncular joint is considerably shorter and also narrower than the 2nd. The 

 flagellum does not fully attain twice the length of the peduncle, and is com- 

 posed of numerous short articulations. The accessory appendage (fig. 3) is 

 well developed, somewhat longer than the last peduncular joint, and com- 

 posed of 5 articulations. 



The inferior antennae are much shorter than the superior, but little ex- 

 ceeding half their length, and have the penultimate joint of the peduncle 

 the largest. The flagellum somewhat exceeds half the length of the peduncle, 

 and is composed of about 9 articulations. 



The oral parts do not differ in any way from those in the other species 

 of Gammarus. 



The gnathopoda (figs. 4 and 5) are moderately strong and rather un- 

 equal in size, the posterior ones (fig. 5) being much the larger. In both pairs 

 the carpus is rather short and expanded distally, forming below a rounded, 

 setiferous lobe. The propodos is in the posterior ones considerably larger 

 than in the anterior, but of a similar form in both pairs, being oval quadran- 

 gular in shape, with the palm somewhat oblique, and defined below by an 

 obtuse angle carrying a strong spine. 



The pereiopoda are of moderate length and have their outer part edged 

 with fascicles of short spines and delicate bristles. The 2 anterior pairs (see 

 fig. 6) are rather slender and somewhat unequal in length, the 1st pair 

 being the longer. The antepenultimate pair (fig. 7) are considerably shorter 

 than the 2 succeeding pairs, and have the basal joint of an irregular oval 

 form, with the infero-posteal corner slightly produced. The last 2 pairs 

 are about equal in length, but differ in the shape of the basal joint, which 

 in the last pair (fig. 8) is somewhat larger than in the penultimate pair, 

 though not very much expanded, exhibiting an oblong quadrangular form, 

 and having the posterior edge, as in the 2 preceding pairs, distinctly 

 serrate. 



The 2 anterior pairs of uropoda (tigs. 9 and 1 0) are of the usual struc- 

 ture, the rami being linear in form and nearly equal-sized. They are edged 

 with a number of coarse spinules and have each at the tip a fascicle of 

 somewhat unequal spines. 



^n3.-MaT. CTp. 213. 35 



