i87 St. Maurice and Ci^aiborne Pelecypoda 187 



Coll. Left valve perhaps 5040, more probabl}^ Lea's figure, 

 was from a reversed tracing of 5039. 



Horizon. — Typically Claibornian, but represented hy muta- 

 tions in beds ranging from the Sabine to the Jackson inclusive. 



Specimens figured. — Paleont. Mus. Cornell Univ. 



Localities. — On the Rio Grande, 2 miles above San Jose and 

 at Webb-Zapata Co. line ; on the Colorado River at Smithville 

 and at the mouth of Alum Creek ; Brazos River, Mosley's Fer- 

 ry, 500 yds below the mouth of Little Brazos ; Cedar Creek and 

 Campbell's Creek, Robertson Co., Texas ; Sabine River, La. ; 

 Hickory ; 8 miles W. of Enterprise ; Wautubbee, Miss. Lis- 

 bon ; Claiborne Bluff, Ala. ; 3 and 6 miles N. W. of 

 Orangeburg, and 5 miles N. of Orangeburg, S. C. ; Ft. Gaines, Ga. 



Corbula compressa Lea, PI. 57, Figs. 1-6 



C. compressa 'Liea, partini, Qont. to GeoL, 1833, p. 47, pl.i, fig. 15. 



C. perdubia de Greg., Mon. Faun. Eoc. Ala., 1890, p. 233, pi. 36, 



figs. 31-32. 

 C. cotnpressa a.nA perdubia Cossm., Notes Compl., 1893, p. 6. 



Lea's original description. — Shell triangular-ovate, compressed, 

 equilateral, inequivalve, concentrically and finely striate on both valves ; 

 beaks slightly elevated, incurved ; umbonial slope with a double carina on 

 the right valve, and a single one on the left ; cicatrices not distinctly 

 marked ; cavitj' of the beaks shallow^. 



Diam .1, Length .2, Breadth 5-20 of an inch. 



Observations. — Not easily confounded with the preceding species, 

 \^gibbosa~\ being smaller and having both valves similarly striate. 



There is considerable doubt in the mind of the writer as to 

 what name should be applied to this very small species of Corbula 

 at Claiborne. Lea's types as preserved in the Academy's collec- 

 tions contained a mixture of compressa, as we understand the 

 term, m,urchiso7ii, and alabamiensis. His figured specimen we 

 fear is but a mutation of alabamiensis and the dimensions he as- 

 signs for the "breadth" of the specimen is quite too large for 

 our species. The name too, compressa, for adult forms is quite 

 misleading, in fact contradictory, it would seem, to the expres- 

 sion '^'^ umbonial slope with a doicble carina on the right valve^\ Yet 

 his "observations" show he had in mind a small species quite dis- 

 tinct from all others, and his types include this among others, 



