g6 Records of the Indian Museum. [Vox,. XXIV, 



Genus Oxynaia Haas. 



1 9 1 3 . Oxynaia, Haas, op- cit., p. 34. 



1913. Oxynaia, Haas, op. cit., p. 152. 



1914. Nodularia (in part), Simpson, op. cit., p. 115. 



Haas established this genus for the species JV. jourdyi, N. 

 diespiler, N. micheloti and N. pugio of Simpson's composite 

 genus Nodularia. Of these I have only seen specimens of 

 Oxynaia pugio, but the descriptions of the other species and my 

 examination of the specimens of 0. pugio justifies Haas' separa- 

 tion of these species into a distinct genus. 



Oxynaia pugio (Benson). 



1862. Unio pugio, Benson, Ann. Mag. Nat. Hist. (3) X, p. 193. 



1889. Unio pugio, Tapparone-Canefri, op. cit. p. 344. 



1913. Oxynaia pugio, Haas, op. cit., pp. 158, 159, pi. xiv, figs. 6, 7. 



1914. Nodularia pugio, Simpson, op. cit., p. 990. 



1915. Nodularia pugio, Preston, op. cit., p. 141. 



This species has a strongly marked and angled posterior ridge 

 running to the cuneate posterior margin ; the shell region tying 

 internal to the ridge between the two valves is nearly flat, but is 

 divided in some specimens by the line of union of the two valves 

 rising in the middle ; both the anterior and posterior margins are 

 very short, the posterior being much the shorter of the two and 

 distinctly cuneate owing to the ventral margin sharply rising up to 

 meet the point of union of the posterior ridge ; the beaks are 

 elevated but not very full. The hinge is characteristic in that the 

 pseudocardinals in the right valve are double, but the anterior is 

 reduced to a thin, lamellar structure only, while the posterior is 

 thickened into a triangular, conical and more or less canine-shaped 

 tooth ; in the left valve also there are two pseudocardinals placed 

 in line with one another, the anterior is small and somewhat coni- 

 cal, the posterior is elongate, ridge-like ox triangular and the two 

 are separated from one another by a fairly deep concavity in which 

 the tooth of the corresponding valve fits. Nothing is known about 

 the anatomy of any of the species of the genus Oxynaia. 



In the Indian Museum the species is represented by a large 

 series of shells from Tenasserim, Pegu, Sawaddy River and from 

 Myadongin Burma. 



A single specimen from Arrakan appears to belong to a distinct 

 variety, but with this scanty material I do not feel justified in 

 describing it as such. 



Genus Physunio Simpson. 



1918. Physunio, Annandaie, Rec. Ind. Mus. XIV, p. 138. 



In the paper cited above Annandaie described two interesting 

 species of this genus from the Inle Basin. The soft-parts of these 

 were described by Ghosh J and further notes on the anatomy were 



' Ghosh, Rec. Ind. Mus. XV, pp. 109-122, pi. xvi (1918). 



