40 



Eatonia peculiaris. (Conrad.) 



Plate 3 A, figs. 2, la^ 26, 2c. 

 Atrypa peculiaris. Conrad, Ann. Rep. Pal., N. Y., 1841. 



Eatonia peculiaris. Hall, Pal., N. Y., vol. 3, p. 244, pi. 38, figs. 21-26, and pi. 101, fig. 'i^, 



1861. 



Description, — Shell sub-ovate ; apical angle from 90? to 100^ ; slope- 

 on each side of the beak either straight or very slightly concave for about 

 one-third the length of the shell ] sides in the anterior two-thirds or three- 

 fourths nearly uniformly rounded ; front irregularly truncated ; greatest 

 width ahttle below the mid-length, — equal to or somewhat greater than the. 

 length. Ventral valve, with a portion equal to about one-third the width in 

 the upper half, and including the umbo, gently convex ; the remainder, con- 

 sisting of nearly the whole of the shell, slightly concave, and with a deep 

 rounded mesial depression, which abruptly elevates the margin of the dor- 

 sal valve, and dies out near the middle of the shell. The beak is very 

 small, incurved, not quite in contact with the dorsal valve. The edge of 

 the shell, from the front margin upwards, is acutely angular, becoming 

 slightly more obtuse and depressed on each side of the umbo. The mesial 

 depression at the front margin is rather more than half the whole width. 

 Near the beak a small portion of the edge of the shell is sharply inflected 

 towards the dorsal valve. The dorsal valve is rather strongly convex j. 

 the middle third of the front, elevated into a short rounded mesial fold,, 

 sometimes with an obscure depression on each side. The umbo is moderately 

 convex, obtusely rounded, the beak buried beneath that of the opposite 

 valve. 



Surface with very fine and obscure radiating striae usually with one 

 much larger than others along the middle of the mesial depression. These 

 markings are so slightly developed, that, to the naked eye, the surface 

 appears to be smooth. 



Length of a largej specimen, ten lines ; width, the same ; length of 

 smaller specimen, seven lines ; width, eight lines. 



Our specimens differ from those that occur in the Oriskany sandstone 

 of Ontario,and also from those^figured in the Pal., N. Y., in having a wider 

 and deeper mesial depression in the ventral valve. This valve, too, is 

 upon the whole more concave than it is in the western specimens. It is 

 much smoother than the Lower Helderberg E. singularis. In all other 

 respects, even to the occurrence of the rib along the mesial depression, it is 

 same. It might be called a variety, but I think not a distinct species. 



Formation ayid Locality. — Indian Cove, Gaspe, No. 8. Also in the 

 Oriskany sandstone in the Township of Oneida, Ontario. In New York 

 it is said to occur in both the Lower Helderberg and in the Oriskany. 



Oaiectors,—^\v W. E. Logan, R. Bell. 



