92 Records of the Indian Museum. [Vol. XXIV 



The author whose work is most open to criticism, however, is 

 Preston, who in two of his works ! dealt with the Indo-Burmese 

 Unionidae. He had for the basis of these works the entire collec- 

 tion belonging to the Indian Museum, which besides being very 

 rich in specimens of various species, is specially valuable because 

 of the many type-specimens or of specimens from type-localities, 

 in many cases named or seen by the authors of the species. 

 Another feature of the collection is the existence of labels in the 

 hand-writings of the various specialists, of whom Blanford, 

 Theobald and Nevill deserve special mention. Nevill in particular 

 had rearranged the whole collection and given provisional names 

 to species and varieties which he considered as new. Preston 

 without any further work accepted NevilPs identifications and 

 under his manuscript names described these species or varieties as 

 new. He did not even attempt to sort out the specimens of 

 different species where Nevill had left large series mixed up, but 

 labelled all the specimens in one lot according to Nevill's label 

 which he found with it. In attempting to revise Preston's work 

 I found that it was quite impossible adequately to work out the 

 Burmese forms without an examination of Tapparone-Canefri's 

 type-specimen?, and I applied to Dr. R Gestro of the Genoa 

 Museum. He was not only kind enough sent me the whole of Fea's 

 Burmese collection on loan, but also generously presented to the 

 Indian Museum specimens of a number of the species, duplicates 

 of which were still available. This kindness on Dr. Gestro's 

 part, for which I am greatly indebted to him, has made it possi- 

 ble for me to assign T.-Canefri's species to their proper generic 

 and specific position. I have besides carefully gone through the 

 large collections of Indo-Burmese Unionidae already in the Indian 

 Museum. 



The results of the work may be briefly summarized here. 

 Most of the forms described by T.-Canefri and Preston were found 

 to be referrable to already known species and I have not come 

 across any new forms. Notes are given on the generic position, 

 relationships, structure and geographical distribution of the 

 twenty-six species and varieties (excluding M. woodthorpi , Godwin- 

 Austen) which I am now able to recognize as being endemic in 

 Burma. They belong to the following genera, Margaritanopsis, 

 Haas; Indonaia, Prashad ; Oxynaia, Haas; Physunio, Simpson; 

 Pseudodon, Gould ; Trigonodon, Conrad ; Indo pseudodon, Prashad ; 

 Parreyssia, Conrad; Lamellidens, Simpson and Trapezoidcus, 



Simpson. 



Genus Margaritanopsis Haas. 



1913. Margaritanopsis, Haas, Nadir. Deutsch. Malakozool. Ges. 

 LXV, p. 33. 



1913. Margaritanopsis, Haas, in -Martini and Chemnitz Co?ich. Cab. 



Unio, p. 121. 



1914. Margaritana (in part) Simpson, Descr. Cat. Naiades, p. 511. 



I Preston, Rec. Ind. Mas. VII, pp. 279-308, pi. viii (191 2) and Faun. Brit. 

 Ind. Freshw.-Moll. pp. 134-195 (1915). 



