41 St. Maurice; and Claiborne Pelecypoda 41 



the Brewery, Monroe. South Carolina : Orangeburg District. 

 Var. sabinica n. var. PI. 18. Figs. 15, 16. 



On the Sabine River, particularly near the township line be- 

 tween 4 and 5 north, though on the Texas side, there is a 

 marked form of pulchra, much more carinate and cuneiform and 

 of much smaller dimensions than typical specimens. In fact, in 

 outline it closely approaches ledoides of Meyer. But, as will be 

 seen by the illustrations it is realh^ not at all closely related to 

 that species. 



Trinacria decisa Conrad, var. PI. 18. Figs. 17-19. 



PI. 19. Figs. I, 2. 



Pedunculus decisus Con, Foss. Shells &c., 1833, p. 39. 



Limopsis decisus Con., Jr. Phila. Acad. Nat. Sci., vol. IV, i860, p. 297- 



8, pi. 47, fig. 16. 

 Probably Trinacria decisa Cossmann, Notes Compl., '93, p. 16, figs. 



17, 18. 



Conrad's original description. — Shell longitudinally suboval, equi- 

 lateral, with obsolete radiating strise ; posterior end obliquely truncated, 

 umbonial slope angulated, incurved ; beaks small, pointed and recurved ; 

 cardinal teeth small and crowded ; series not much arcuated ; margin en- 

 tire. Ivcngth y^ an inch. 



We have no specimens from the Claiborne "sands" that 

 could be referred to this species. However, Cossman has illus- 

 trated a small, seemingly rather flat specimen with fine radiating 

 lines clearly referable to a variety of decisa. In the Orangeburg 

 District, S. C. we have several much larger specimens of the 

 same general type, one to which we have given the name Caro- 

 lina (fig. 18, a). With it, however, are forms becoming much 

 shorter proportionally, and deeper, and having the umbones 

 more deflected posteriorly, these we styled var. abbreviata (fig. 

 19). They show by their general configuration and faint, broad 

 ribs (often bifurcate) that they are very closely akin to the spec- 

 imens of this species occurring rather sparingly with declivis at 

 the base of Claiborne Bluff and at Lisbon (see illustrations, pi. 

 18). 



Horizon and localities. — St. Maurice : Base of bluff at Clai- 

 borne and Lisbon, Ala. ; Cedar Cr., Wheelock league ; Colorado 

 River at Smithville ; Trinity River at Alabama Bluff ; Brazos 



