ioo Records of the Indian Museum. [Vol. XXIV, 



being confined to Burma. Most, of these Burmese species, though 

 the}' show near relationships with the other Indian species of the 

 genus, form a definite group among themselves. 



Parreyssia bhamocnsis (Theobald). 



1873. Unio bhamoensis, Theobald, Joarn. As. Soc. Bengal XI. II, 



pp. 207, 208, pi. xvii, fig. 1. . 



1876. Unio bhamoensis, Hanley and Theobald, Conch. Ind. p. 62, 



pi. civ, fig. 2. 

 187s. Unio bhamoensis (in part), Nevill, in Anderson's Zool. Res. 



Yunnan Exped. p. 900. 

 1890. Unio bhamoensis, Faciei, Conch Sam. Ill, p 146. 

 1899 Unio bhamoensis, von Martens, Arch. Naturgesch. LXV, pp. 



3 8 » 39. P l - v » fi g s - 2 ) 4. . 



1900. Parreysia bhamoensis (in part), Simpson, Proc. US. Nat. Mas. 

 XXII, p. 483- 



1914. Parreysia bhamoensis, Simpson, Descr Cat. Naiades, pp 1111, 



1112. 



1915. Parreysia {Parreysia) bliamoensis, Preston, Faun. Brit, Ind- 



Freslnv. Moll, p 163. 



The type-specimen of this species from Bhamo, with the 

 label " U. Bhamoensis n. sp." written in Theobald's hand, is pre- 

 served in the Indian Museum collection. The species was stated 

 to be a rare one, and Theobald considered it and U. mandelayen- 

 sis, the species described next to it, to form " a natural little 

 subgroup of osculent species," which, however, he did not feel 

 " justified in separating from the great Indian conugatus group. " 

 Nevill, while working out the Yunnan collections, did not agree 

 with Theobald's conclusions and united the two species U. bha- 

 moensis and U. mandelayensis under the former name. Tappa- 

 rone-Canef ri, ' in his paper on the Burmese molluscs collected by 

 Fea, agreed with Nevill in his interpretation of Theobald's two 

 forms, but wrongly selected the name U. mandelayensis for the 

 species. I have examined one of Tapparone-Canefri's specimens 

 and find that it is a true mandelayensis. Von Martens, who 

 published good figures of this species, considered the species 

 U. bhamoensis as distinct from U. mandelayensis. Simpson in his 

 first work united the two species under the name P. bhamoensis , 

 and in this was followed by Preston ; in his later work, however, 

 having examined more specimens, he rightly regarded the two 

 species as distinct. 



I have examined the types of the two species besides a largt 

 series of specimens in the Indian Museum and find the following 

 differences between the two species : — (i) The shell of P. bha- 

 moensis is only sub-triangular as opposed to the distinctly tri- 

 angular shell of P. mandelayensis, (ii) the beaks in P. bhamoensis 

 are high but not placed well forwards, (iii) in young shells of 

 P. bhamoensis the beaks and the umbonal region have only a 

 faintly marked zigzag radial sculpture which extends over the 

 posterior wing and a little on the anterior side, but no tubercles 



l Tapparone-Canefri, Ann. Mas. Civ. Stor. Nat. Genova, XXVII, p. 342 

 (1889). 



