170 



UMONID.l- 



.subveiiti'icose, concentrically zoned with bluish green and ochra- 

 ceous yellow, rather glossy, smooth, except at the umbones, which 

 are adorned with longitudinally divergent slender corrugations, 

 the hinder lines of which incline interiorwards, the front ones 

 posteriorwards ; a few similar wrinkles radiate subtransversely 

 thence to the dorsal end of the concave anterior slope ; ventral 

 edge convex ; front dorsal edge straightish, a little elevated ; 

 extremities rounded, the front rather broad ; nacre silvery ; 

 umbonal cavity ample ; teeth laminar, compressed. 



Long. 19, lat. 2G-o mm. 



Hah. Assam. 



The species was originally described from a single valve : below 

 are given the dimensions of two specimens in the British and 

 Indian Museums collections respectively : — 



1. 2. 



Long . . 16-7o 19 mm. 



Lat 25'5 30 mm. 



Diam 13 14-75 mm. 



The above two specimens are the only ones which the compiler 

 of the present volume has been able to examine ; though agreeing 

 in the essential characters with the original description, there are 

 still considerable differences between them : the smaller, or British 

 Museum specimen, being far more obtuse posteriorly than that of 

 the Indian Museum, the dorsal margin of the former gradually 

 sloping upwards posteriorly to a rounded angle, while in the latter 

 this character is not nearly so accentuated. 



304. Parreysia (Parreysia) burmaniis {lUanfonl). 



Parrt'i/sia {Fdrrei/i-ia) //unnaniisiVAAuiord); Simpson, Wasliingtoii, 

 1).0., Smiths, inst., Nat. Mii.s. Proc. xxii, lUOO, ]>. 84o. 



Unio burmauug, Blanford, P. Z. S. 18G9, ]>]>. 449-450. 



Unio biniumuf', H. v't T., ('. I. ]f<7V>, ]). l!», pi. 42, Hg. 1 ; Ptetel, 

 Conch. S;im. iii, 1890, p. 140. 



Original description: — Testa subovata, solida, subcompressa, 

 valde insequilateralis, picea vel fusco-olivacea, concentrice plicato- 

 striata, disco medio et postico rugis obliquis irregulariter angulatis, 

 interdum granosis, hie illic praesertim versus marginem ventraleni 

 obsoletis corrugato ; umbouibus non prominentibus, subplanulatis, 

 angulatim corrugatis, baud procul ab extremitate anteriore positis; 

 hniella parva, concava ; latere antico brevissimo subacuminato- 

 rotundato ; area convexa ; margine dorsali postice regulariter 

 convexo-curvato, terminaliter rotundato, ventrali convexo ; den- 

 tibus cardinalibus crassis, radiatim corrugatis, in valva dextra binis, 

 anteriore minimo, in sinistra ternis vel subternis ; lateralibus 

 elongatis subcurvatis, in valva dextra subduplicibus, in sinistra 

 duplicibus ; margarita colore salmonis tintta. Testa junior 



