CONCHOLOGIA INDICA. 



PLATE IX. 



SPATHA, PSEUDODON, TRIGONODON, 

 T7NIO. 



1. S. Soleniformis, Benson (as Anodon), Journ. 

 Asi. Soc. Bengal, vol. 5 (1836, Nov.), p. 749. 



Cacliar. 

 If this shell is a true Mycetopus, its specific name 

 must be changed, as D'Orbigny published his M. Sole- 

 niformis in 1835 (Guerin's Mag. Zool.) : it closely 

 approaches the M. (?) emarginatus of Lea. 



2. P. inoscularis, Gould, Proc. Bost. Soc. Nat. 

 Hist. vol. 1, p. 160 (as Anodon), 161. — Unio 

 Vondembuschiana, Reeve, Conch. Icon. Unio, 

 i. 518, badly (from this specimen). 



River Salwen, Birmah. 



May possibly prove identical with the Margaritana 

 Vondembuschiana (Lea, Trans. Amer. Phil. Soc. vol. 8, 

 pi. 18, f. 39,) a supposed Javanese species. 



3. T. crebristriatum, Anthony, Amer. Journ. Cone, 

 vol. 1 (1865), pi. 18, f. 1 (as Monocondylaia). — 

 Unio c. Reeve, Conch. Icon. Unio, f. 517. 



British Birmah. 



4. P. Salwenianum, Gould, Proc. Bost. Soc. Nat. 

 Hist. vol. ], p. 158, 160 (as Anodon and Pseudo- 

 don) : Otia, p. 193. — Unio S. Reeve, Conch. Icon. 

 Unio, f 513. 



Salwen River, Birmah. 



5. T. crebristriatum, var. Anthony. 



The Monocondi/laa Peguensis of Anthony (Amer. 

 Conch. Journ. vol. 1) seems a form of this rather 

 variable species. 



6. U. lamellatus, var. Lea. 



A peculiar winged forni (like Wahlamatensis of 

 Lea) from Mandelay. 



Judging from the examination of many hundred 

 specimens of Indian Uniones, confirmed by long and 

 peculiar study of thousands of North American Naiades, 

 we are compelled to believe that the teeth and muscular 

 impressions of each species are so liable to modification 

 through age and casualties as scarcely to present any 

 permanent defining character. Not but that they 

 merit examination, as the vividly green variety of 

 triembolus can instantly be discriminated from cwru- 

 gatus by its dentition. 



According to our notions cesi-uleus, marginalis, favi- 



dens, corrvgatus have been unnecessarily subdivided, 

 and several species founded on diseased or eroded 

 shells; but as our aim is to indicate the names which 

 have been applied to the several forms, we shall pro- 

 ceed to figure the more striking ones, never erasing a 

 species from our lists without having traced it to its 

 root by indisputable links. 



PLATE X. 

 UNIO. 



1. Unio olivarius, Lea, Trans. Amer. Phil. Soc. 

 ser. 2, vol. 4 (Obs. on Unio, vol. 1, p. 113), pi. 16, 

 f 38.— Hanley, Recent Bivalve Sh. p. 195, pi. 22, 

 f 32.— Kuster, ed. Chem. Unio, pi. 82, f. 2. 



Rohilcund Streams. 



2. 4. U. macUentus, Benson, An. Nat. Hist. ser. 

 3 (1862), p. 187. — U. occatus. Lea, Journ. Ac. 

 Nat. Sc. Philad. 1863 (Obs. on Unio, vol. 10), 

 pi. 50, f 304.— Reeve, C. Icon. Unio, f 412. 



"Bengal;" Mandelay. 

 The somewhat worn condition of the type (figure 2) 

 prevented Lea from identifying the species. 



3. TJ. radula, Benson, in Hauley's Recent Bivalve 

 Sh. p. 382, pi. 2.3, f 41. 



Assam. 

 Benson's unique type (with part of the ferruginous 

 coating removed), from which Mr. Hanley drew up his 

 description, has been once more figured. 



5. U. smaragdites, Benson, An. Nat. Hist. ser. 3, 

 vol 10 (1862), p. 190. 



Burhampooter River, Assam. 



So rare a sheU that the original types are the only 

 examples known to us. 



6. TJ. Bonneaudi, Eydoux and Souleyet, Guerin's 

 Mag. de Zool. 1838, pi. 119, f 1. 



Bhama, Upper Birmah (Blanford). 



A very scarce shell, lent to us by Mr. Blanford, 

 whose incomparable series of Indian Unionea was most 

 liberally placed at our disposal. 



7. U. pugio, Benson, An. Nat. Hist. ser. 3, vol. 10 

 (1862), p. 193, Reeve, C. Icon. Unio, f 516. 



Ava; Pegu (Theobald). 

 A rare shell which cannot be confused with any 

 other of the known Indian Uniones. 



