175 S'^- Maurice and CIvAiborne Pelecypoda 175 



very closely allied to parilis Con. , though not so inflated nor so 

 erect, but of double the size of this latter species. In the Jack- 

 son at Jackson, Miss., the small, rugged specimens are very 

 erect and angular. 



7>/>^.— Phila. Acad. Nat. Sci. (Conradian Coll.) 



Horizon. — Claiborne, St. Maurice and ? Sabine. 



Specimens figiwed. — From Claiborne sand. Now at Cornell. 



Localities. — Claiborne and Lisbon (as var. bistriata), Ala.; 

 Wautubbee, Miss. ; also Hammett's Branch, La. 



Spisula prsetenuis Conrad, PI, 53, Figs. 5-8 



Madra prretenuis Con., Foss. Sh. Tert. Form., 1833, p. 42, pi. 19, fig. 



9 of Harris' Reprint. 

 31. prcztejiuis Con., Amer. Jour. Sci., vol. i, 1846, p. 217, pi. 2, fig. 4. 

 Mactrella prcetenuis Con., Amer. Jour. Conch., 1865, p. 4. 

 Spisula prcEtenuis Ti2X\, Trans. Wag. Ill, 1895, p. 896. 



Conrad's best description (Amer. Jour. Sci.). — Subtriangular, com- 

 pressed, equilateral, thin and fragile, umbonial slope submarginal, subrec- 

 tilinear, carinated ; beaks slightly prominent : posterior slope with two 

 prominent fine lines and obliquely rugose ; surface of the valves with v%xy 

 minute concentric closely arranged lines. Claiborne, Ala. 



This shell is very rare. It has somewhat the outline of M. delunibis, 

 of the Miocene, but is a much smaller and very distinct species. It has the 

 cardinal fissure which would constitute it a member of the genus Scisso- 

 destna. 



Conrad's illustrations show a somewhat longer or more de- 

 /w7;z(5z.y-like form than the usual specimens from the "sand" at 

 Claiborne. The Orangeburg specimens are not quite so sharply 

 carinate and are thicker accordingly than the typical Claibornian 

 (var. azcstralina, n. var., pi. 53, figs. 9-12). 



Type. — Phila. Acad. 



Horizon. — Jackson, Claiborne and St. Maurice Eocene. 



Specime7is figured. — From Claiborne and Orangeburg, now 

 in the Paleont. Museum at Cornell. 



Localities. — Claiborne sand, Claiborne, Ala. ; three to six 

 miles N. of Orangeburg, (more or less silicified specimens in fer- 

 ruginous clay), S. C. ; specimens here are fairly abundant. Ft. 



