AMI'HIPOD CRUSTACEA OF THE GENUS GAMMARUS 65 



(2) The form of the lower hind corners of the second and third pletjn somites. With 

 regard to this character Sars (op. cit.) writes that "last pair of epimeral plates of metasome 

 but very little produced at the lateral comers." Stebbing (op. cit., p. 474) also describes 

 them as "simply ciuadrate." On the contrary, Chevreux ( 1908, p. 98 ) , who studied an Asiatic 

 race of this species, pointed out that the lower posterior angle of the third ])leon somite is 

 prolonged and sharply pointed. y\ similar description is also given by Chevreux and Fage 

 (1925, p. 254). Tattersall (1914, p. 213) also shows that the specimens of G. pulcx from 

 the Pamirs at an altitude of 15,600 feet have the third pleon somite with a considerably more 

 produced and pointed lower hind angle than figured in Sars' monograph. 



The present specimens from North India, especially those from the localities nos. K1-L76, 

 have also the third pleon somites with considerably produced lower hind corners, such as is 

 seen in those described from high alpine regions in Asia by the above-mentioned authors. In 

 this feature the present specimens are much more allied to Gaiiunarus occllatus described by 

 Martynov (1930) from Lake Issyk-koul in Turkestan than to the typical form of G. pule.v. 

 This prolongation is more marked in the specimens from the lower Kashmir localities 

 (Plate IV, figs. 1-7) than those from the high Ladak localities (Plate IV, figs. 8-10), and 

 the specimens from the localities L 78 to L 82 (Plate IV, figs. 11, 12) have the third pleon 

 somite with much less produced angles which remind us of those of the typical form of 

 G. pule.v as figured by Sars. 



The number of spinules on the lower margins of the third pleon somite is in luost cases 

 6, l_)ut varies rather considerably from 3 or 4 to 9. 



(3) The number of spinules on the last three pleon somites. In most cases 2 median 

 dorsal and a pair of 2 lateral spinules are present on each side of both first and second pleon 

 somites. On the last somite the median dorsal spinules are usually absent or with only a 

 single median. The specimens of Togom Tso (L49, the highest Ideality) and Ororotse Tso 

 (L 52) have only 1 or 2 median dorsal and one pair of lateral spinules, or even none devel- 

 oped at all. Some examples of the arrangement of these spinules in the specimens from 

 various localities are shown in Table 2. 



(4) Telson. The telson is usually a little longer than the length of the peduncles of the 

 third uropods, except a few cases (e.g., L81), in which the telson is nearly as long as the 

 peduncles of the third uropods. The specimens with the former type of telson, viz., longer 

 telsons, are very closely allied to Martynov's Gainiuants ocellatiis (loc. cit.). Both lobes of 

 the telson are more elongated and provided more richly with setae in the specimens from the 

 lower Kashmir localities (Plate V, figs. 1-4) than in those from the higher Ladak localities, 

 especially from L 78-L 82 (Plate V, figs. 5-7). Thus the specimens from the last-named locali- 

 ties have the telson of the typical form of this species, while the form of the telson of those 

 from the lower localities rathet resembles that of G. ocellatus. 



The telson has usually 2 or 3 terminal spines, as seen in Table 2. A single lateral spine 

 near the base of each \o\x figured by Sars is not seen in the present specimens. 



(5) The inner ramus of the third uropod (Plate V, fig. 8) is usually shorter than the 

 outer ramus, aljout 4/5 of the latter. The arrangement of the spines and fringes of plumose 

 setae on both rami varies considerably in the specimens from different localities. 



(6) The form and size of the second joints of the last three pereiopods are rather differ- 

 ent not only in both sexes collected in the same locality, but also in the specimens from differ- 

 ent localities. (lencrally, the s]iecimens from the lower Kashmir localities have the pereiopods 



