NEW SPECIES OF MOLLUSKS OF THE GENUS COR- 

 BICULA FROM URUGUAY AND BRAZIL 



By William B. Maeshall, 



Assistant Curator, Division of Mollusks, United States National Museum 



In my paper " New Uruguayan Mollusks of the Genus Corbicula " ^ 

 I described: 



Corbicula {Cyanocyclas) ei-rcularis. 



Corbicula {Gyamocyclas) co'mpacta. 



Corbicula {Gyanocyclas) delicata. 



Corbicula {Gyanocyclas) exquista. 



Corbicula {Cyanocyclas) felipponei. 



Corbicula {Cyanocyclas) fortis. 



Corbicula {Cyanocyclas) oleana. 



Corbicula {Cyanocyclas) fayscmduens-is. 

 Specimens from Brazil, which.were already in the Museum collec- 

 tion, and many specimens, all of them from the Department of 

 Colonia, Uruguay, and nearly all from the Bay of jColonia in the Rio 

 de la Plata, lately received from Prof. Auguste Teisseire, Directeur 

 du Lycee Departemental de Colonia, make it necessary to describe 

 six new species. 



In many specimens of Corbicula there are radiating splashes of 

 purple along the interior edge of the ventral margin. When these- 

 occur there should be a corresponding ray, usually of reddish, on: 

 the outer surface and often such rays will be revealed by careful 

 examination although at first their presence may be unsuspected. 

 In same specimens in which there are rays it is impossible to detect 

 them, because of a thickening of the periostracum which makes it 

 nontranslucent. In such cases if the periostracum be removed the 

 rays will show clearly on the white background ; or if a longitudinal 

 section of the shell be made dots of color will show where the rays, 

 were cut. When radiating splashes of purple occur along the ventral 

 inner edge they are a sure sign that rays, even though invisible,, 

 are present on the outside, and it is unnecessary to remove the 



J 1924, Proc. U. S. Nat. Mus., vol. 66, art. 15, pp. 1-12. 



No. 2699.— Proceedings U. S. National Museum, Vol. 72, Art. 3. 



55217 — 27 1 



