igz St. Maurice and Claiborne Pelecypoda 191 



a gibbosa Lea, PI. 58, Figs. 1-6 



C. gibbosa Lea, Cont. to Geol. , p. 46, pi. i, fig. 14, 1833. 



C. oniscus Con. {partim) Amer. Jour. Sci., vol. i, p. 398. pi. 4, fig. 3. 



C. ignota de Greg., Mon. Faun. Eoc. Ala., p. 232, pi. 37, figs. 14-18. 



Left valve only. 

 C. gibbosa de Greg., idem, p. 233, pi. 36, figs. 27-28 and 29-30? (Right 



valve only). 

 C. gibbosa Har., Bull. Am. Pal., vol. i p. 20, 1895. 



Lea^s original description. — Shell very transverse, somewhat inflat- 

 ed, nearly equilateral, very inequivalve, on the right valve transversely 

 and distinctly striate, on the left valve transversely and minutely striate ; 

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

 right valve, and on the left a single carina and indistinct fold. Cicatrices 

 not distinctl}- marked ; cavity of the beak rather deep. 



Diam. .2 Length .3 Breadth .5 of an inch. 



Observation.-;— This species has some resemblance to the murchisoni, 

 but differs in being more transverse, in being more produced behind, in 

 having a more obtuse carina, and in being less inflated, 



While at first there may seem to be a little superficial resem- 

 blance between this species and imirchisoni, especially in the 

 heavy liration over the surface of the right valve, no one could 

 well confound specimens of the left valves of the two species. 



The illustrations herewith given show how very distinct the 

 forms are. 



Conrad included not only murchisoni but gibbosa and even 

 the Jacksonian species from the Ouachita River, La. , under his 

 oniscus. 



Type. — Of right valve, 5063, of left 5064 of the Phila. Acad. 

 Coll. 



Horizon. — Claiborne sand. 



Specimens figured. — Paleont. Mus. Cornell Univ. 



Corbuia murchisoni Lea, PI. 58, Figs. 7-10, 12-15 



C. oniscus Con., Amer. Jr. Sci., Jan. 1833, vol, 23, p. 341 ; idem, '46, 



vol. I, p. 398, {partim) non pi. 4, fig. 3. 

 C. murchisoni Lea, Cont. to Geol., Dec. 1833, p. 46, pi. i, fig. 13. 

 C. jnurchisoni Ae^ Qr&g., Mon. Faun. Eoc. Ala., 1890, p. 231, pi. 37, 



figs. 22-39, Pl- 38, figs. 1-13. 

 C. murchisoni Cossm. , Ann. Geol. et Pal., 1893, p. 6. 

 C. oniscus Ball, {partim), Wag. Inst. Sci., Ill, pt. 4, 1898, p. 843. 



