NODULARIA. 139 



Margaron (Unio) occatus, Lea, Syn. 1870, p. 31. 

 Unio macilentus, Benson, A. M.'N. H. x, 1862. p. 187 ; H. & T., 



C. I. p. 5, pi. 10, fig. 2, & p. 62, pi. 154, fig. 5.' 

 Unio rugosus, H. & T., C. I. p. 62, pi. 154, fig. 3. 



Original description: Testa plicata, elliptica, rugoso-occata, 

 compressa, valde insequilaterali, postice biangulata, antice regu- 

 lariter rotundata ; natibus prominulis, valde compressis, ad apices 

 plicis, pulchris divaricatis ; epidermide luteo-oliva et valde rugosa; 

 dentibus cardinalibus parvis, compressis, obliquis ; lateralibus 

 sublongis subcurvisque ; margarita alba et valde iridescente. 



Hab. Bengal (W. A. Haines). 



The dimensions given below are those of a specimen in the 

 British Museum with locality " Bengal," which, although some- 

 what larger than that figured by Lea, agrees well with his figure 

 and description. 



Long. 22, lat. 42, diam. 15-25 mm. 



It may here be noted that, upon examination, the specimen 

 no\v in the British Museum, figured by Hanley in the ' Concho- 

 logia Indica ', pi. 10, fig. 4, and which was most probably copied 

 by Sowerby in the l Conchologia Iconica ' on pi. 79, fig. 412, 

 proves to be a very immature example of a totally different 

 species. 



270. Nodularia (Nodularia) pachysoma (Benson). 



Nodularia (Nodularia} pachysoma (Benson); Simpson, Washington, 

 D.C., Smiths. Inst, Nat. Mus. Proc. xxii, 1900, p. 813. 



Unio pachysoma, Benson, A.M.N.H. x, 1862, p. 186; H. & T., 

 C. I. 1876, p. 6, pi. 12, fig. 1. 



Margaron ( Unio) pachysoma, Lea, Syn. 1870, p. 63. 



Unio pachystoma y Paetel, Conch. Sam. iii, 1890, p. 162. 



Original description : Testa transverse ovato-elongata, insequi- 

 laterali, tenuiuscula, valde tumida, antice brevi rotundata, postice 

 breviter alata, demum modice acuminata, margine ventral! 

 subrecto, postice ascendente ; disco laeviusctilo, polito, transverse 

 striatulo, postice dense striato ; epidermide viridi, fasciis nonnullis 

 luteis radiisque obscuris ornata, postice cserulescen ti -viridi ; um- 

 bonibus prominentibus versus apices contiguos minute radiato- 

 costatis, carina umbonali prominente obtusa, linea secunda 

 radiata interjacente ; dentibus cardinalibus duplicibus, laminatis, 

 lateralibus modice elongatis, valvae sinistra} solum duplicibus : 

 margarita pallide purpurea, interdum salmonis colore tincta. 



Long. 23, lat. 44, diam. 22 mm. 



Hab. Brahmapootra Eiver, Assam ; also Sawaddy, Burma 

 (Indian Museum Coll.). 



The anterior cicatrices are distinct, the posterior confluent, the 

 dorsal ones under the cardinal teeth. The inner lamina of the 

 latter in the left valve is sometimes obsolete. 



It differs from U. cceruleus in being more inflated and-devoid of 

 radiate corrugations on the slopes, the posterior side is excavated 



