( 6 ) 



Inhabits Penang, and stretches into Tenasserim, or even further 

 north. 



Chaibassia. 



Nov sub-Q-enus. 



Habit of Geomyda, but zygomatic arch complete. 



G. tricarinata, Blyth. J. A. S., vol. 24, p. 714 (1855). 



Oeomyda tricarinata, Blyth. 

 Nuchal plate rather elongate. Jaws simple, not serrated. 

 Vertebrals sharply keeled. Costals keeled superiorly, the keels 

 parallel in front, but converging on the fourth costal. Shell 

 broadest across the centre of the fourth costal. The two outer 

 fore-claws small. Pupil black, iris umber brown. Colour of 

 shell, above ruddy brown, deepening to blackish ; below yellow- 

 ish ; the two colours sharply confined to the two surfaces. Keels 

 and margin pale yellow. Head and neck, brownish, with an 

 orange stripe from the nostrils over the eyes, and a paler patch 

 towards the base of the mandible on either side. 



Shell of male, 5-00 long, 32-5 broad, 2-25 high. 

 Shell of female, GdO long, 400 broad, 300 high. 

 Inhabits Chaibassa. The Naga Hills, North Assam. 



Blythe's type was from Chaibassa. The two living specimens 

 (for the examination of which I am indebted to the courtesy of 

 J. Wood-Mason, Esq.) were forwarded by Major Godwin Austen 

 from the Nao-a Hills. 



I cannot agree with Dr. Jerdon's suggestion (P. A. S., B., 

 March 1870) that the figure of E. Belangeri Less in the " Voyage 

 aux Indes Orientales Rep., pi. 1, p. 291 (1834) represents this 

 species ; but concur with Giinther, who regards it as representing 

 M. trijuga. The colouration of the sternum is precisely that of 

 M. trijuga, as distinguished from G. tricarinata. The present 

 species may be readily distinguished from trijuga during life by 

 the colours of its eye, the iris of which is brown, whereas the iris 

 of trijuga is white. The fore-claws too in trijuga do not vary 

 much in size, whereas the outermost fore-claw in this species may 

 be almost termed minute, the next to it being also small ; and this, 



