418 



PROCEEDINGS OF THE ACADEMY OF 



[Part II 



slopes the rugosity is greater. Posteriorly a few minute short 

 wrinkles run more obhquely towards the basal margin. In suitable 

 light, very weak traces of radial sculpture are discernible. It 

 was probably very little alate in front of the beaks, but the shell is 

 broken away there. 



Length 44, alt. 40, diam. 23.7 mm. 



Type no. 2763 A. N. S. P. 



The type is an excellent specimen except for some breakage of the 

 anterior margin. The hinge is not visible, but the characters, so 

 far as shown, are those of a Lucinid shell and not of a Cardium. 



There is also a broken and distorted specimen. 



Divaricella proletaria Pils. and Johns. Plate XLII, flg. 1, 2. 



Divaricella proletaria P. & J., Proc. A. N. S. Phila. 1917, p. 198. 

 Lucina dentata Wood, Gabb, Trans. Amer. Philos. Soc, xv, p. 251. 



D. prevaricata Guppy is of the same size, but according to Dall 's 

 figure of the type (Proc. U. S. N. Mus., XIX, plate XXX, fig. 4) it 

 has closer divaricating grooves. 



DIPLODONTIDAE. 



Diplodonta (Phlyctiderma) gabbi Dall. Text-fig. 43. 



Mijsia suhquadrata Gabb, Trans. Amer. Philos. Soc, xv, 1873, p. 252. Not 

 Diplodonta suhquadrata Carpenter, P. Z. S., 1855, p. 230. 

 D. [iplodonta] gabbi Dall, Trans. Wagn. Inst., iii, p. 1183, footnote. 

 Diplodonta {Phlyctiderma) pundurella Dall, t. c, p. 1183. 



Externally this species has an extreme- 

 ly minute, irregular but dense puncta- 

 tion, the pits more or less anastomosing, 

 forming a sort of network where most 

 perfectly preserved. There is some vari- 

 ation in contour, some examples having 

 the anterior end less rounded than that 

 figured. The largest valve (figured) 

 measures, length 5.6, alt. 5.4, diam. 1.65 

 mm. 



Type is no. 2693 A. N. S. P. 

 We have not compared specimens of the Bowden D. punctureUa 

 Dall, which from the description and figure appears not to differ 

 from gabbi. Dall had not seen the latter, apparently. 



Fig. 43. Diplodonta 

 gabbi Dall. Type. 



Diplodonta dedecoris n. sp. Text-flg. 44d.e. 



Proc. A. N. S. Phila. 1917, p. 198. 



