258 Records of the Indian Museum. [Vor Vv, 
Potamon in the above synopsis refers to the subgenus only, 
the type of which is P. potamios. The species of this subgenus, 
as here limited, range from S. Europe, N. and E. Africa, and 
Madagascar, all through S. Asia, to China and the Malay Archi- 
pelago; but the subgenus is not represented in the peninsular part 
of India. 
Polamiscus has hitherto been found only in N. E. India and 
Tongchuan Fu. 
Geotelphusa ranges from Japan and §. Asia to N. and E. 
Africa. It may occur in Australia, but the only two Australian 
species attributed to Geotelbhusa which I have been able to exam- 
ine belong to the Gecarcinucine group Liotelphusa. It does not 
occur in the Indian peninsula, Kingsley’s Geotelbhusa enodis being, 
as I have lately ascertained by examination of specimens, a 
Liotelphusa. 
Hydrotelphusa is peculiar to Madagascar. It is very like 
Potamon, but the thickening at the base of the terminal joint of 
the mandibular palp is more than ordinary prominent, and the 
sixth abdominal segment of the adult male is not so broad. _ 
Potamonautes is confined to Africa; the Indian species that 
have been referred to Potamonautes belong to other groups. 
Platytelphusa (= Limnotelphusa, Cunnington) is peculiar to 
Lake Tanganyika. 
Acanthotelphusa is well represented both in KE. Africa and S. 
Asia. It has not been found in the peninsular part of India. 
Parapotamon seems to be restricted to L. Yunnan Fu. It in- 
cludes two species—P. endymion and P, spinescens. In the former 
the merus of the external maxillipeds is somewhat longer and 
narrower than usual, and the exopodite of these appendages is non- 
flagellate; in the latter this is not the case. Parapotamon is, 
undoubtedly, closely related to Acanthotelphusa, but has the post- 
orbital crests almost obsolete. 
Evimetopus, which is also a very near relative of Acanthotel- 
phusa, is restricted to West Africa. 
Subfamily DECKENIINA. 
This subfamily comprises a single genus, Deckenia, with three 
constituent species, two of which are found in E. Africa and one 
in the Seychelles. The Seychelles species, judging from Miss 
Rathbun’s figure, is a good deal unlike the other two. 
No doubt the prolongation of the efferent branchial canals, 
which encroach on the epistome and alter the set of the antenne 
and antennules, gives these crabs a peculiar appearance; but it 
seems to me that the ends of classification would be best served by 
placing Deckenia with the Potamonine. 
Subfamily GECARCINUCINAS 
In all the members of this large subfamily the mandibular 
palp is divided into two lobes, a dorsal and a ventral: the dorsal 
