9 



species has been found in the Western Himalayas or in the North-west 

 Frontier region. 



e. The subgenus Liotelphusa. The type of this subgenus, which includes 

 five Indian species and varieties, is Paratelphusa (^Liotelphusa) Icevis (W.-M.). 

 Three species belong to the Eastern sub-Himalayan region. One belongs to 

 Burma. One belongs to the Peninsula. 



/. The subgenus Glohitelphusa includes six species and varieties. Three 

 are restricted to the Eastern sub-Himalayan region. Three are restricted to 

 the western edge of the Peninsula. None is found in Bm-ma. 



No species either of Liotelphusa or Glohitelphusa are found in the Western 

 Himalayas, or in the North-west Frontier region, or in the Indo-Gangetic Plain. 



3. The genus Gecarcinucus. This genus is closely related to the subgenus 

 Barytelphusa of the genus Paratelphusa. It includes three species, all of 

 which are restricted to the western edge of the Penin.sula. The only other 

 species known is from New Guinea, ^t^j-^^w^^ 



To look at the matter from the converse side : the Indian fresh-water crabs 

 appear to hang together in six territories, as follows : — 



(1) A Western Frontier Territory, including Baluchistan, the North-west 

 Frontier, and the north-west corner of the Punjab (Salt Range). Here we 

 find only — (1) the subgenus Potamon (varieties of the common palcearctic 

 species P. fluviatile Latr.), and (2) in the southern portion of the territory a 

 species of the subgenus Paratelphusa — a species which, though in some respects 

 quite singular, seems to be a derivative of P. spinigera. 



(2) A Western Himalayan Territory, extending perhaps as far eastwards 

 as Nepal. Here we find only- — (1) species of the subgenus Potamon (species 

 which are closely related to P. fluviatile), and (2) one species of the Paratel- 

 phusa subgenus Barytelphusa. 



(3) A North-eastern Frontier, or Eastern Himalayan, or Eastern sub- 

 Himalayan Territory, including Sikkim, Bhutan, and the lower Brahmaputra 

 drainage system. In this territory there occur representatives of every 

 subgenus of Potamon and of every subgenus of Paratelphusa that exists 

 within the boundaries of the Indian Empire : in short, we find everything but 

 Gecarcinucus. It looks as if this territory had been the motherland of the 

 Indian branch of the family. Whence it was originally stocked is by no means 

 clear ; nor does it look as if it could have been stocked at one time and by one 

 movement. It has certain very characteristic features of its own, for the 

 details of which I refer to the appended Geographical List; it has certain 

 intimate relations with the Malayo-Burman territory which, as they are 

 specific, point to a recent connexion with that territory : and it has certain 

 strong resemblances to the Malabar territory which, as they are in no case 

 specific, would rather indicate an anterior connexion with that territory. 



