1922.] B. Prashad : Burmese Unionidae. 95 



ovate, less inflated and have the sculpture more pronounced. 

 For the present I propose considering this species as distinct, 

 but believe that it will only turn out to be a form, of I. bonneaudi 

 when more material is collected. 



Indonaia pachysoma (Benson). 



1914 Nodularia pachysoma, Simpson, op. cit., p. 987. 

 1915. Nodularia pachysoma, Preston, op. cit., pp. 139, 140. 



I. pachysoma is nearly related to I. bonneaudi and I. caerulea. 

 From the former it is distinguished by its more elongate, more 

 inflated, but less deep shells, more pronounced umbones and much 

 stronger hinge, while from the latter it differs in having much 

 brighter and more inflated shells and in the entire absence of the 

 radial sculpture on the sides. 



The species has practically the same distribution as I. bonne- 

 audi and is represented in the Indian Museum by a large series 

 of specimens from the Brahmaputra River, Assam, and the Irra- 

 wadi River, Burma. 



Indonaia crispata (Gould). 



1914. Nodular ia crispata, Simpson, op. cit., pp. 994, 995. 



1915. Nodularia crispata, Preston, op. cit., p. 142. 



Gould's original description is very short but Simpson has 

 recently given an elaborate description. It is a very character- 

 istic form and is easily distinguished from all other Burmese 

 species of the genus by its sculpture, which consists of green 

 zigzag radial lines interspersed here and there with thicker nodules 

 on a yellowish to brownish ground ; the ridges run transversely in 

 the anterior region and vertically in the posterior part of the 

 shell. 



In the Indian Museum collection the species is represented 

 by specimens from Bhamo (Burma), Siam and Cambodia. 



Indonaia crispisulcata (Benson). 



1914. Nodularia crispisulcata, Simpson, op. cit., p. 1017. 



19 1 5. Nodularia (Radiatula) crispisulcata, Preston, op. cit., pp. 146, 



147. 



Simpson in 1900 separated this species along with his N. lima 

 to form a new section. Radiatula, of the genus Nodularia; but as 

 I have recently ' shown there is no justification for separating i". 

 lima from species like /. caerulea and I. bonneaudi. Nothing is 

 known about the anatomy of I. crispisulcata and I do not consider 

 the shell characters alone as being sufficient for the separation of 

 this species into a distinct section. 



The species, as represented by a large series of shells from 

 Bongong River, Burma, in the Indian Museum, is remarkably 

 constant in the sculpture of the shell. 



1 Prashad, Rec. Ind. Mus. XXII, p. 604 (1921). 



