70 AMIMIH'on CRl'STACKA OK T 11 K CF.NUS CAM MARTS 



etc. From tlie first-n.-iiiR'd lake. Marlyiuiv (l'*3C)j alsn recorded (/. piilc.v t(}t;ether with two 

 other new species and mie new sul>s])ecies (see foregoing- chapter). Tattersall (1914) first 

 recorded this species in the region north of India near the western ])art of Tibet. He found 

 C. pitlcx in a collection made in a pool on the summit of Killik Pass hetw'een the Northern 

 Hunza Range and the Taghdunkash, Pamir (15,600 feet) and in pcmls near the hanks of the 

 Killik River. The former locality is the highest hitherto recorded as the habitat of G. piilc.v. 

 Therefore, the discovery of this species in Togom Tso (5334 meters or 17,506 feet) on the 

 western border of Tibet by the Yale North India Expedition may lie stated to give a new 

 record, surpassing the altitude nf the I'aniir locality nunti(}ned ahoNc. Tiie Russo-German 

 Pamir Expedition in 1928 also collected G. pulex which was examined by I)r. A. B. Martynov.^ 



In the other parts of Asia, especially east of India, we have only a few records of this 

 species. Tattersall (op. cit. ) noted its occurrence in Lake Tali V\\ (Erh Hai, Shan-kuan), 

 Yunan, China, at an altitude of c. 7000 feet. In Japan G. piilcx, first recorded by Tattersall 

 (1922) from Lake Biwa, is common everywhere, though in the northern parts it is replaced 

 by G. annandalci Tattersall which is also distrilnited in China ( Tai-Hu, Shanghai). 



As described in the foregoing chapter, the (/. pulcx of Lake Issyk-koul has some peculiar 

 characters compared with the typical form of the species, and the specimens of the same 

 species collected by* the Yale North India F.xpedition resemble rather closely those from Lake 

 Issyk-koul. It is supposed from this fact that such races of G. pulcx are rather w'idely s])read 

 in the vast areas of the high alpine regions in Asia. 



6'. ocrllatus, G. occllatus minor and G. bcrgi are the representative races of the North 

 Indian and Turkistan dift'erentiation of G. pulcx in Asia. The races of the typical form are 

 distributed in the plain areas from h'urope to Japan. The centre of distribution of the alpine 

 races is not ascertained at present. 



B. Distribution in Kashmir and Ladak, and Its Limiting Factors 



As seen from a glance at the list of the localities in which G. pulcx was collected 

 (Table 1), its distribution in North India is very peculiar and interesting. The species is 

 common in Kashmir at altitudes up to alx)ut 1600 m. It is however quite absent in the lower 

 parts of Ladak to the east of Kashmir ( 1600-3800 m. above sea level), Init it reappears again 

 near the Tiljetan borders at altitudes over 3800 m. It is fpiite common in the lakes of these 

 high alpine regions, among which Lake Togom Tso is the highest locality, as mentioned 

 already. I shall discuss below shortly the very interesting problem as to what factors might 

 cause such a peculiar regional distribution. 



1. Physical and Chemical Factors 



A number of physical and chemical determinations made on waters from manv locali- 

 ties during the expedition is summarized in the following table (Table 4). 



a. Water temperature. The water temperature does not seem to limit the occurrence of 

 G. pitlcx in the area investigated, since it ranges from O'C. to as high as 22 ^C. As generally 

 known, this species is an eurythermal ubiquitous crustacean. 



° These specimens from Pamir differ from the typical form of (he species by having somewhat larger eyes 

 (Dr. Martynov, personal communication dated May 27, 1933). 



I 



