66 AMPHIPOD CRUSTACEA OF THE GENUS GAMMARUS 



"^ TABLE 2 



Arrangement of Spinules on the Last Three Pleon Somites and the Number of 



Apical Spines of Telson- 



3-5 with narrower and more elongated second joints. The iiind margins of the second joints 

 in these limhs are much more convex in the female (Plate III, figs. 5-7) than in the male 

 (Plate III, figs. 8, 9), but their lower hind angles are roundcil in Ixith sexes. The second 

 joints in these limbs show a tendency to become reduced in length in the specimens from iiigher 

 altitudes (Plate \T). For instance the specimens from L 49 have the last three pereiopods 

 with the rather short second joint about 2/3 to 4/5 as wide as it is long, so that they resemble 

 very closely tliose of typical G. pule.v; their lower hind corners are somewhat ])roduced, their 

 hind margins more convex and the front margins often without spines or setae. 



(7) The length and the number of the joints of the fiagellum of the first antenna. 



The length of the first antenna is nearly as long as or a little shorter than half of the 

 body in the specimens from the high Ladak localities, Imt in the specimens from the lower 

 localities it is often much shorter than half of the body. The number of joints in the first 

 antenna shows considerable variations, as SpanJl (1923 and 1924) noticed in some luiropean 

 forms of this species. Some examples are sliown in 'J'able 3. In larger individuals this 

 fiagellum is composed of 25-28 joints, often reaching as many as 38 joints in some large 

 specimens from the lower localities, while the specimens from the very high IcKalities (L49, 

 L 52, etc.) have flagella of a much smaller numlier of joints. 



" The figures between two annnias are the number uf median dorsal spinules. 



