No. 109.] 157 



Spirifer eatoni ( n. s.). 



Pal. N.Y. Vol. iv. 



Shell transversely oval, one-half to two-thirds as long as wide ; 

 hinge equalling the greatest width of 'Jic shell, obtusely angular 

 at the extremities : dorsal valve very convex in the middle, 

 nearly semicircular, rising into a moderately prominent rounded 

 or slightly flattened mesial fold ; beak and narrow area distinct- 

 ly incurved : ventral valve the more convex, most prominent 

 near the beak; mesial sinus moderately rounded ; beak small, 

 somewhat abruptly arcuate ; area high, slightly arcuate just 

 below the beak ; foramen narrow, partly closed above by a 

 pseudo-deltidiura. Surface marked by about nineteen simple 

 rounded plications on each side of the mesial fold and sinus, and 

 crossed below the middle of the shell by imbricating laminae 

 of growth. 



This shell ditTers from S. granulifera in the following characters : It 

 is smaller, with a higher and much less arcuate area, and has no dLstinct 

 longitudinal depression on the mesial fold ; the mesial sinus is also smaller 

 and more angular at the margins, while the beak of the ventral valve is 

 less arched and prominent. 



The only specimens I have seen of this species are somewhat exfoliated ; 

 so that I have no means of determining positively the character of the 

 finer markings of the surface, but it was probably granulated as in S. 

 granulifera. 



In form and in the number of plications, this species approaches S. eu- 

 rufines of Owen ; but it differs in having the beak and area of the ventral 

 valve more arched, the lateral slopes of the area more rounded, the dorsal 

 valve more convex, and the shell generally thinner. 



Geological position and locality. Hamilton group, Erie county ; and 

 stores of Seneca lake. 



Spirifer clintoni (n. s.). 



Pal. N.Y. Vol. iv. 



Shell semicircular, gibbous in the central region, much compressed 

 at the extremities of the hinge, width nearly twice the length; 



