138 Contributions to Indian Malacology. [No. 2, 



M. testa ovali rugosd, extrinsecus virescente, intus rnargaritaced : 

 cardinis dente primario crenulato, laterali longitudinal), alterias 

 duplicate 



No. 3. — Unio marginalis, Lam. Bengal. 



Lam. VI. 79, No. 41. 



Kiister, Mart, and Chem. p. 239, PI. 80, f. 4. 



This species is probably the most widely distributed of all the 

 Indian forms. It is extremely variable, and I am inclined to believe 

 that many of the species to be hereafter enumerated are merely 

 varieties of it. I have examined the type and compared a shell from 

 Pegn with it, which will be figured. It agrees very well. Krister's 

 figure represents a variety with unusually prominent umbones, and 

 rather longer from the hinge to the ventral margin than usual. 



TJ. marginalis is by no means confined to India. It abounds, as I have 

 already mentioned, in Pegu. One of Lamarck's forms came from Ceylon, 

 and Kiister appears much disposed to unite to it a species from the Nile 

 in Egypt. Lamarck's type was said to inhabit rice-fields in Bengal. 



No. 4. — Unio anodontinus, Lam. Bengal. 



TJ. anodontina, Lam. VI. 80, No. 47. 



U. anodontinus, Kiister, Mart, and Chemn. p. 240, PL 80, f. 5. 



Lea has classed this shell as identical with TJ. marginalis, Lam. 

 If Krister's figures in the Conchylien Cabinet can be trusted, the two 

 shells differ more than any one of Lea's three species, bilineatus, lamel- 

 latus, and Bengalensis do from each other, or from marginalis. Most of 

 the Bengal specimens of marginalis, however, are intermediate between 

 the two forms figured by Kiister as marginalis and anodontinus. 



The locality given by Lamarck for this species is Virginia. 

 I unfortunately omitted to examine the specimen when I had the 

 opportunity of doing so. There is. I believe, no question but that 

 the shell was really from India. 



No. 5. — Unio favidens, Bens. Ganges valley and Burhampooter 

 valley, Assam. 



Benson, Gleanings in Science, I, PI. 8, f. 1. 



„ Ann. Mag. Nat. Hist. 1862, 3rd Ser. X. 188. 



This species has been frequently confounded with TJ. corrugatus, 





