34 BuivivKTiN 31 34 



acterized species. 



Lithophaga ciaibornensis Conrad, PI. 17. Figs. 10, 11. 



Lithodomus claiborne7isis Con., Jr. Phila., Acad. Nat. Sci., vol. i, p. 



132, pi. 14, fig. 27, 1848. 

 Lithophaga ciaibornensis Con., x\nier. Jr. Conch. , vol. i, 1865, p. 11. 

 Lithodomus ciaibornensis Aid., Bull. Amer. Pal., vol. i, p. 69, pi. 6, 

 fig. 14. 

 Conrad's mnginal description. — Very thin and fragile, inflated ; pos- 

 terior hinge margin obliquely truncated, the extremity regularl)^ rounded ; 

 lines of growth distinct. 



Locality. — Claiborne, Alabama. 



We give herewith as fig. 11 a copy of Conrad's figure in the 

 Journal of the Philadelphia Academ3^ The ti'pe specimen, about 

 I by yi in. long is still in the Academy's Collection. Likewise an- 

 other, rather cjdindrical fragment. Aldrich's figure, here given 

 as fig. 10, has a somewhat different form from Conrad's, but re- 

 garding this matter he makes no comments. 



This must certainly be regarded as one of the most rare spe- 

 cies at Claiborne. Gregorio, Cossmann, Dall and ourselves have 

 had access to no new material. 



Lithophaga petricoloides Lea, PI. 17. Figs. 12, 13. 



Byssoraia petricoloides Lea, Cont. to Geol., 1880, p. 48, pi. i, fig. 16. 

 Lithodomus petricoloides De Greg., Annal. de Geol., et Pal., 1890, p. 

 184, pi. 22, figs. 7 and 8. 



Lea''s original descj'iption. — Shell subcylindrical, very thin, very 

 transverse, indistinctly striate, on the posterior part obliquely and obsolete- 

 ly folded ; beaks scarcely perceptible ; posterior and anterior cicatrices per- 

 ceptible. 



Diam. . . . Length. i. Breadth .3 of an inch. 



Observations. — V/ith much doubt I have placed this shell in Cuvier's 

 genus Byssoniia. It agrees better with his description of that genus than 

 any one I know. Unfortunately I have obtained but a single valve and 

 that is imperfect. It has a strong resemblance to Petricola pholadiformis 

 (Lamarck) {P.fornicafa, Say), but is to appearance entirely without teeth, 

 having several irregular folds about the beak. It differs also in the exterior 

 folds or ribs, which are, in the pholadiformis, marked and situated on the 

 anterior part. 



The figures herewith given are from de Gregorio. He 

 seems to have found some nearl)^ perfect valves. The generic 

 position of this form is still in some doiibt. Fragments in our 



