153 St. Maurice and Claiborne Pelecypoda 153 



interior porcellanous, giving the shell a slightly thickish appear- 

 ance for so small a specimen ; anterior adductor scar apparent 

 but not deeply impressed, posterior and pallial sinus excessively 

 faintly defined ; margin faintly crenate anteriorly ; in the right 

 valve (the only one obtained) there is a faint trace of a long pos- 

 terior lateral tooth, but a corresponding anterior channel, if ever 

 present, is entirely eroded away. 



This single specimen vi'as found among some St. Maurice 

 material marked Sabine River ?, La. Its exact provenance is 

 therefore undetermined at present. 



At this early date this genus seems not to have developed all 

 the marked characteristics shown later on in the Oligocene and 

 higher beds. 



The external ligament was very short. As the shelly matter 

 decaj'ed there was a slight pit-like cavity formed just under the 

 beak, reminding one of the more extensive expansion seen under 

 the beak of Dosinia, Dosiniopsis, etc. 



Marcia retisculpta Meyer, PI. 47, Figs. 16-19 



Venus retisculpta Meyer, Bull, i, Geol. Sun^ Ala., 1886, p. 84, pi. 

 I, figs. 27, 27 a. 



Meyer's original description, — Rhombically circular ; convex ; cov- 

 ered with broad, flat, and somewhat irregular concentric lines, crossed by 

 similar radiating ones ; the sculpture indistinct near the umbo ; an im- 

 pressed line separates a long lunule ; pallial sinus large ; margin entire. 



Locality. — Claiborne, Alabama. 



The sculpture makes the surface appear as if reticulated with small, 

 rounded holes, especially in worn shells ; the figured specimen shows the 

 complete hinge, otherwise it is not the largest or best sculptured one. 



The species is beautifully marked with fine pits concen- 

 trically and divaricately arranged. Our two specimens are fig- 

 ured to show the dentition of both valves. This species seems to 

 belong to Cossmann's section Textivenus. From the Claiborne 

 sand bed. 



Petricola claibornensis, n. sp , PI. 48, Figs, i, 2 



Specific characterization . — General appearance as figured ; 

 rather small (15 x 8 x 3.5 mm.); exterior surface with irregular 



