UNIO. NODULABIA. 135 



pseudocardinals compressed ; beak cavities well excavated, not 

 compressed. Animal highly coloured, anal opening crenulate or 

 smooth." 



265. Unio mongolicus, Middendorff. 



Unto mongolicus, MiddendorfF, Sib. Reise, ii, 1851, p. 277, pi. 27, 

 figs. 7, 8 ; Hessling, Perl, und Ihre Perlen, 1859, p. 203 ; 

 Sehrenck, Reise und Forsch. im Amur-Lande, ii, 1867, p. 699 : 

 Westerlund, Kong. Svensk. Vet.-Ak. Handl. xiv, no. 12, 1876, 

 p. 74 ; Paetel,"Conch. Sam. iii, 1890, p. 159 ; Westerlund, Faun, der 

 Pal. ii, pt. 7, 1890, p. 113. 



Original desertion : Testa transversim oblonga, subreniformi, 

 ttimescente, fusca ; latere postico anticum quater superante ; mar- 

 gine ventral! nonnihil retuso ; margine cardinali primo ventrali 

 parallel! et turn, inde a dimidio latitudinis, in rostrum asyminetri- 

 cum, inferum, descendente ; umbonibus prominulis, erosis ; den- 

 tibus cardinal! bus par vis, crassiusculis ; dent! bus lateralibus 

 evolutis. 



Long. 32, lat. 76, diam. 24 mm. 



Hob. A mountain stream at Gorbitza in Daurien. 



There is a single specimen in the National Collection which 

 is indistinguishable from that in the Indian Museum from the 

 Upper Indus. 



Genus NODULARIA. 



Nodularia, Conrad, Proc. Acad. Nat. Sci., Philadelphia, vi, 1853, 

 p. 268 ; Simpson, Washington, D.C., Smiths. Inst, Nat. Mus. 

 Proc. xxii, 1900, p. 806. 



TYPE, Unio douylasice, Gray ; China. 



Range. China; Japan; Eastern Siberia; Indo-China; India; 

 Borneo ; Java ; Sumatra ; New Guinea ; Africa. 



Shell nodose ; cardinal teeth robust, single in the right valve ; 

 in each valve the principal cardinal tooth is parallel with the 

 lateral teeth, or directed towards the posterior extremity of the 

 shell. 



Section NODULARIA (sensu stncto). 

 See above. 



266. Nodularia (Nodularia) digitiformis (Sowerby). 



Nodularia (Nodularia) digitiformis (Sowerby) ; Simpson, Washing- 

 ton, B.C., Smiths. Inst., Nat. Mus. Proc., xxii, 1900, p. 809. 



Unio digitiformis, Sowerby, Conch. loii. xvi, 1868, pi. 65, 

 fig. 333 ; Pjfitel, Conch. Sam. iii, 1890. p. 150. 



