MARYLAND GEOLOGICAL SURVEY 697 



Genus AENONA Conrad 

 [Am. Jour. Conch., vol. vi, 1870, p. 74] 



Type. Tellina eufalensis Conrad. 



" Equivalved, without fold ; hinge character, two compressed very 

 small, widely diverging teeth in the right valve; lunule very narrow, 

 lanceolate, and marked by a deeply impressed line." Conrad, 1870. 



Restricted in its known distribution to the Cretaceous. 



EUFALENSIS Conrad 

 Plate XLII, Figs. 3, 4 



Tellina eufalensis Conrad, I860, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 



iv, p. 277, pi. xlvi, fig. 15. 

 Tellina eufalensis Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 14. 



JEnona, eufaulensis Conrad, 1870, Am. Jour. Conch., vol. vi, p. 74. 

 ^Enona eufaulensis Whitfield, 1885, Mon. U. S. Geol. Survey, vol. ix, p. 168. 



pi. xxiii, figs. 2, 3. (Hinge incorrectly drawn.) 



^Enona eufaulensis Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 16. 

 ^Enona eufaulensis Weller, 1907, Geol. Survey of New Jersey, Pal., vol. iv, 



p. 623, pi. Ixx, figs. 24, 25. (Hinge incorrectly drawn.) 



Description. " Subtriangular, convex, entire, inequilateral ; anterior 

 end subtruncated ; hinge margins equally declining ; summit not promi- 

 nent ; posterior end acutely rounded ; left valve furnished with one bifid 

 and one rudimentary cardinal tooth; lateral distinct." Conrad, 1860. 



Type Locality. Eufaula, Alabama. 



Shell thin, polished, very fragile, rather compressed, transversely elon- 

 gated, subtrigonal in outline, subequilateral ; umbones slightly bulbous at 

 their tips, orthogyrate, placed a little behind the median line; umbonal 

 angle not far from 135; anterior slope a little more gentle and a little 

 more produced than the posterior; base line evenly and gently arcuate; 

 external surface smooth, excepting for a few incremental striations near 

 the base; bands of concentric color markings frequently retained, the 

 umbones being, as a rule, darker than any other portion of the shell ; liga- 

 ment external, opisthodetic, the nymph short and rather slender; hinge 

 plate narrow; armature of left valve moderately concentrated, consisting 

 of a short laminar cardinal fused anteriorly with the dorsal margin and, 



