I 



792 PROCEEDTXGS OF THE NATIOXAL MUSEUM. vouxxiii. 



The family comprises the following genera: 



DIPLODONTA Bronn, 1831. 



Type, Venus lupinus Brocchi. 



UNGULINA Daudin, 1802. 



Type, U. rubra Roissy. 



FELANIA Recluz, 1851. ' 



Type, Venus diaphana Gmelin. 



JOANNISIELLA Dall, 189S. 



Type, Cyrenella oblonga Sowerby. 



Of these genera only Dlplodonta is represented in American waters, 

 as far as yet known, and it is divisible into the following groups: 

 Section Dijplodonta s. s. Type, D. lupinus Brocchi. 

 Section Felardella Dall, 1899. Type, Felmim mta Gould. 

 Shell like Dlplodonta^ but heavy, compressed, smooth externally, 

 with a conspicuous usualh" dark periostracum and less equilateral 

 valves. 



This group exists well developed in the Eocene. The species called 

 Felania bj^ Carpenter, from American waters, are included in it. The 

 type is from Japan. 



Section Phlyctiderma Dall, 1899. Type, Diplodonta semiaspei'ci 

 Philippi. 

 Shell like Diplodonta, except that the surface, in addition to incre- 

 mental sculpture, is punctate, pustulate or subreticulate. The type is 

 from Cuba, but the group is world wide. 



Section Sphcerella Conrad, 1838. Type, 8. sitbvexa Conrad= 

 Eryc'ina subconvexa d'Orbigny 1852, not Lucina suhvexa Conrad, 1848. 

 Shell large, concentrically striate, an impressed line above the anterior 

 cardinal, suggesting a minute lunule; the right posterior cardinal 

 wide, undulated above, the posterior adductor scar distant from the 

 hinge plate. The type is Miocene, and there is one recent species 

 known from the Atlantic coast; D. Verrill! Dall, 1900. 



Genus UNGULINA Daudin. 



This is Ungidlna Daudin,^ sole example U. ri<5*'« Roissy ^ and Clothe 

 Basterot, 1825, not Faujas St. Fond, 1808. 



The type is TdUna cuneata Spengler,^ but not of d'Orbigny, 18-15. 

 This specific name must be adopted in place of the more familiar 

 rubra of Roissy. The Ungidina transversa of Lamarck,* is united by 

 Deshayes with Lamarck's U. ohlonga, and both are identical with 



'Bosc, Hist. Nat, Coq., Ill, 1802, p. 86. 



^Idem, pi. XX, figs. 1, 2. 



"Chemnitz, Conch. Cab. VI, 1782, p. 135, pi. xiii, fig.131. 



* Animaux sans Vertebres, V, 1818, p. 487. 



