62 EUI.LETIN 31 62 



Leda opuienta Conrad, PI. 23. FiJ,^«. 20-22. 



Nucula opuienta Con., Foss. Sh. Tert. Form., )833, p. 46. 

 Nuculana opuienta Con., Am. Jr. Conch, vol. i, 1865, p. 13. 

 Leda opuienta Dall, Trans. Wag. &c.. Ill, 1895, p. 578 and 587. 



Conrad's original description.- — Elongated, compressed with regular, 

 concentric sulci ; anterior side rostrated, and with a submarginal carinated 

 line ; space between it and the margin with regular, prominent striae ; beaks 

 posterior to the middle. 



7>/>^.— Phila. Acad. Nat. Sci. 



Specimens figured. — Paleont. Mus. Cornell Univ. 



Localities and horizo7i. — St. Maurice (var. compsa Gabb).- Rio 

 Grande, 6 miles above Starr-Zapata Co. line ; Brazos River, Mos- 

 ley's ferry, 60 yards below mouth of Little Brazos andon the Lit- 

 tle Brazos on Mosley's ferry road ; Cedar Cr., N, E. Cor. Wheel- 

 ock League; Campbell's Cr. , Robertson Co.; 3 miles N. E. 

 Crockett, Houston Co.; Collard's Farm, Town Branch, Brazos 

 Co. ; San Miguel Cr., S. E. Cor. Frio Co., Tex. ; Monroe well, 

 1200 ft. deep. La. ; 6 miles W. N. W. of Orangeburg, S. C. 



Var. hamtnetti : Hammett's Branch, La. (pi. 23, fig. 23). 

 Claiborne (tj'pical): Claiborne sand, Claiborne, Ala. 



In the varietal form referred to a distinct species {compsa, Jr. 

 Acad. Nat. Sci. Phila., vol. 4, i860, p. 387, pi. 67, fig. 57) by 

 Gabb the space "with regular prominent striae" is wider than in 

 the Claiborne form ; the shell itself, however, is usually' smaller 

 (pi. 24, figs. 1,2). 



The new variety hamtnetti is smaller, more robust and ar- 

 cuate. 



Leda magna Lea, II. 24. Figs. 3, 4. 



Nucula magna Lea, Cont. to Geol., Dec, 1833, p. 197, pi. 6, fig. 211 



Lea's original description. — It is ventured to place this name upon 

 the fragemnt of a A'ucula, which differs on the exterior, very much, from 

 any species, fossil or recent, which has come under my notice. It possesses 

 transverse folds on the sides, which lie closely to, and are beautifully par- 

 allel to each other. These terminate in a smooth plane, on the umbonial 

 slope which is flattened. A straight furrow, or channel, passes along the 

 posterior dorsal margin, in which are striae, slightly oblique. The posterior 

 series of teeth so far as it exists in the fragment, is straight, and possesses 

 nineteen angular teeth. From the appearance of this part of the series, I 

 should not be surprised if it possessed almost as many more. The substance 



