NEW PEARLY FRESH WATER MUSSELS FROM SOUTH 

 AMERICA. 



By William B, Marshall, 



Assistant Curatoi; Division of Mollvsks, United States National Museum. 



This paper is based upon three sendings to the United States 

 National Museum of naiads from South America. They are: 



A collection made by Dr. C. Wythe Cooke, of the United States 

 Geological Survey, in the Province of Santander, United States of 

 Colombia. This has yielded a new species, DiplodonUtes cookei^ 

 which necessitates the erecting of a new genus for its reception, 

 and another new species, Anodontites colovibknsis. 



Another lot comes from Dr. Henry Pittier, of the Bureau of 

 Plant Industry of the United States Department of AgTiculture, 

 which, among other things, contains a new species, Anodoiitites 

 pittierl, from Venezuela. 



In addition to these there are also here described five new species, 

 Biplodon subcylindricus, D. suhquadratus, D. arcuatus, D. trivialoi- 

 des, and M onocondylaea felipponei^ from Uruguay. These are part 

 of a splendid series of specimens recently donated to the United 

 States National Museum by Dr. Florentino Felippone, of Montevideo. 



DIPLODONTITES, new genus. 



Naiads without lateral teeth and with pseudocardinal teeth of 

 the character of those Dlflodontites cookei herein described and 

 as yet the only known species of the genus. The sinulus is like 

 that of the genus Ajiodontites. 



The most important features of this genus lie in the hinge char- 

 acters. The triangular sinulus and the absence of lateral teeth dis- 

 tinguish it from the genus Diplodon, while the presence of pseudo- 

 cardinal teeth distinguish it from the genus Atwdontites. On the 

 other hand, the possession of the pseudocardinals may indicate 

 some relationship to Diplodon while the nature of the sinulus may in- 

 dicate some relationship to Anodontites. Thus, by shell characters, it 

 stands between the two genera mentioned. In North American naiads 

 a somewhat similar condition is found. Some of these have pseudo- 

 No. 2437-Proceedings U. S. National Museun, Vol. 61. Art. 16. 



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