14 Bulletin 31 14 



variet}' of scllceformis, pcrplicata from "Eocene, Caton's Bluff, 

 Conecuh River, Alabama ; L. C. Johnson." This is an inalate 

 form of the same stock as our lisbonoisis. The description reads : 



"Shell very heav}^ arcuate triangular, with coarse, rounded, 

 numerous divaricating ribs (twenty-five to forty), no auriculation 

 or posterior sinuosity of the margin near the hinge, the upper 

 valve extraordinaril}' ponderous, the general form regular and 

 uniform, the valve margins nearly or quite simple. 



The figures herewith shown are of "Co-types" kindly fur- 

 nished b>- Dall, and are in the U. S. Nat. Mus. collection. 



Ostrea vicksburgensis, var. ludoviciana. n. var. PI. 10, figs, i-io 



In Conrad's description of O. vicksburgensis he gives no 

 characteristics that would neccssarilj' demand that this variety 

 be referred to this species. The description { Proc. Acad. Nat. 

 Sci. Phila., 1847, P- 296) reads as follows : 



Plicated ; very irregular and adhering, the upper valve not flat, but 

 swelling in an irregular manner. Height \j{ in. 



Their is nothing peculiar about this shell, yet it is clearly distinct 

 from any other species of the American Tertiary hitherto described. 

 Common. 



This species is again described in the Journal of the Acad- 

 emy, (vol. I, p. 126) and a figure is given (pi. XIII, fig. 5) but 

 with this additional information the .species would still be ill de- 

 fined. 



It has sometimes been referred to O. panda Mort. on accotmt 

 of fig. 10, pi. 19, of Morton's Synopsis. The name /«?z^a, how- 

 ever, applies only to the species from the vicinit}' of St. George's 

 on the Delaware and Chesapeake canal, referred primarily by 

 Morton (1830, A. J. S. vol. 17, p. 2S4) to oisfagal/i \\\t\\ a. ques- 

 tion, and figured as such in vol. 18, pi. 3, fig. 22. The name 

 panda was proposed in 1833 i^id. vol. 23, p. 293) for this Cre- 

 taceous species. In 1834, in the "Sjmopsis &c" Morton includes 

 several Tertiary specimens under the name panda and figures one 

 on pi. 19, fig. 10. Gabb, 1861, (Proc. Phila. Ac.) seeing this 

 impropriet}' proposed the name mortoni for the Tertiarj' speci- 

 mens. An examination of the specimens in the Phila. Academy 



