202 Records of the Indian Museum. [Vol. XVI, 1919.] 



ovotestis {ov.) largely developed, its convolutions being very- 

 large and ample, diminishing in size as they approach the albmnen 

 gland {al. gld.). The male organ is not unlike that of Hemiplecta 

 ftoweri (plate iv, fig. 6a). 



Radula (text-fig. 2 A, A'). — No marked differences in the 

 form or size separates the central and marginal teeth, they 

 merge gradually one into the other. The centre tooth and about 

 12 on either side are on broader plates. They are succeeded by an 

 enormus number of narrow, curved, aculeate, closely-packed teeth, 

 and neaiing the margin a few become evenly and minutely bicus- 

 pid, the outermost marginals are very minute. The first radula 

 extracted was not complete enough to count the teeth in the 

 row, but there are at least 250 on each side. 



This does not agree with the radula of the species I dissected 

 and described in the Proceedings of the Malacological Society, p. 35, 

 of a specimen from Saigon given me by Dr. Hungerford, who 

 retained the shell. Dr. Hungerford' s collection was dispersed 

 after its sale to Messrs. Sowerby and Fulton, so there is no fear of 

 ever tracing and seeing what that shell was like. 



Jaw very dark brown, perfectly straight on the cutting edge 

 and slightly arched above (text-fig, 2 B) It may be noticed par- 

 ticularly that in the genitalia the male organ of this Siam species 

 is not at all like that of the South Indian genus Ariophanta with 

 dextral shells, with which they have been placed by some con- 

 chologists. 



Among the large Molluscs of the Malayan Region, this species 

 does not find a place in either of the genera Hemiplecta, Xesta, or 

 Rhysota. Thus it seems necessary to constitute one, which I 

 name after the Siam district in which it is found. 



Koratia, gen. nov. 



Shell very large and solid, animal with no shell lobes, mucous 

 gland small. Jaw straight on cutting edge. Radula, teeth numer- 

 ous in row, with closely-packed, aculeate marginals. 



If we consider one character, a marked external one, that of 

 shell lobes, it is of interest to note that Hemiplecta humphrey- 

 siana bears the same resemblance to Koratia distincta as Macro- 

 chlamys indica and allied species do to Bensonia monticola. 



