244 



SYNOPSIS OF THE AMERICAN SPECIES OF THE 

 FAMILY DIPLODONTID^E. 



By W. H. DALL. 



(Read before the Society, April 12th, iE 



The family Diplodontidae comprises the genera Felania, Diplodonta, 

 Ungulina, and Joannisiella. 



The Cryptodontidas, which have been by some authors united with 

 this group, possess very remarkable anatomical characters and should 

 be kept separate. Joannisiella has long been confounded with 

 Cyrenoidea, from which much misconception has arisen. The former 

 is a brackish water Diplodonta with a flattened foot, the latter belongs 

 to a distinct group. The typical Felania is close to Diplodonta, but 

 many Lucinoid shells have been mistakenly referred to Felania. 



Genus DIPLODONTA, Bronn, 1831. 



EAST AMERICAN SPECIES. 



Section Diplodonta, s.s. 

 Type Venus lupinus Brocchi ; not Diplodon Spix, 1827; Mysia Brown, 

 Conrad et al., not of Leach; Glocomeue Leach, 1852; Cydadicama 

 Val., 1854; Mitt re a Gray, 1857 ; Egeria sp. Lea, Cyrenella sp. Sby. 



1. D. punctata (Say as A??iphidesma, 1882). D. veneznelensis 

 Dkr., 1848; + D. janeirensis Rve., 1850; + D. subglobosa C. B. Ads., 

 1852; + D. b/aziliensis Mittre, 1850; + D. oi'bella Gabb, non 

 Gould, 1 88 1 ; + Mysia pellucida Heilprin, 1889. 



Range. Cape Hatteras to Southern Brazil. Also Pleistocene. 



2. D. nucleiformis Wagner, 1838; + D. elevata Conr., 1845; 

 + D. carolittensis Conr., 1875. 



Range. Coast of the Carolinas, 15-52 fathoms, living ; also fossil 

 in the Miocene of Virginia and N. Carolina. 



Section Felaniella Dall, 1899. 

 Type Felania usta Gld. Shell like Diplodonta but heavy, compressed, 

 externally smooth, with a conspicuous dark periostracum and less 

 equilateral valves. 



3. D. candeana d'Orbigny, 1846. 

 Range. Marco, Florida, to Brazil. 



4. D. vilardiboana d'Orbigny, 1846. 

 Range. Brazilian and Argentine coasts. 



Section Phlyctiderma Dall, 1899. 

 Type D. semiaspera Philippi. Shell like Diplodonta, but with the 

 surface more or less punctate or pustulate. 



