I860.] Contributions to Indian Mai neology. 151 



correct position of these species, if the hinge teeth are trustworthy- 

 indicators of generic affinity. H. and A. Adams, in the Gen. Rec. 

 Moll., include under Monocondylaea, M. Vondenbuschiana, Lea, from 

 Java,* described by Lea as a Margaritana (Baphia of Adams) and 

 several species of the genus have been described from Siam and 

 Cochin China by French and American naturalists. 



I have received from Mr. Theobald fine specimens obtained in Pegu 

 which correspond admirably with Margaritana Vondenbuschiana, Lea, 

 and unquestionably belong, I think, to that *species ; and also shells 

 which appear to belong to a variety of Anodonta inosctdaris, agreeing 

 with the type in size, shape and every character of importance ; and 

 not only are the two forms unmistakeably congeneric, but I even 

 think it probable that specimens might be met with to unite them 

 specifically, as they differ in no essential character, except the very 

 different degree of development of the cardinal tooth, which in 

 Vondenbuschiana is scarcely raised, while in the specimens which I 

 refer to inoscularis it is sometimes nearly a quarter of an inch high. 



There are in the Asiatic Society's collection, also, two forms which 

 appear to me certainly varieties of M. Vondenbuschiana. One of them, 

 however, agrees more closely with the figure of M. Cumingii, Lea 

 (Jour. Acad. Nat. Sci. Phil. 2nd Ser. IV, 235, pi. 33, f. 114) a Ma- 

 lacca shell, which only differs from Vondenbuschiana in unimportant 

 minutias. 



M. Vondenbuschiana is described and figured by Lea in Trans. Am. 

 Phil. Soc. VIII, 222, pi. 18, f. 39, and also in Kuster. 



Were there nothing but the form of the hinge teeth to connect the 

 South American species of Monocondylcea with the Burmese and Java- 

 nese Pseudodon and Margaritana, especially having regard to the very 

 diverse form of the shell, I should suspect them to be in reality distinct 

 types. But there is one little peculiarity which appears to tend to 

 unite them. At the termination of the portion of the hinge line in 

 which, by close inspection, flattened obsolete representations of the 

 lateral teeth may be seen, there is a very peculiar expansion of the 

 end of the ligament which covers a small sinus in the inner surface of 

 both valves. This is very well shewn in Lea's figure of Margaritana 



* Yet they state, " All the species of this genus known are from the river3 

 of South America." 



