FOREIGN JURASSIC STOMECHINI. 221 



Dimensions. — Height, three tenths of an inch ; transverse diameter, six tenths of an 

 inch. 



Formation. — Bathonien, " dans les couches calcaires du Forest-marble, de Montillot, 

 Yonne." Cotteau. 



Collection. — M. Cotteau, a single specimen. 



Stomechinus polyporus, Agassiz. Syn. Echinus polyporus, Agassiz. Catalogue syst, 



p. 12. 



Test hemispherical, circular depressed ; ambulacra with four rows of tubercles ; inter- 

 ambulacra with close-set tubercles at the base and circumference, which rapidly diminish 

 on the upper surface. It is distinguished from Stomechinus bigranularis by having four 

 rows of tubercles in the ambulacra. 



Formation. — Bathonien de Ranville? Rare. 



Collection.— M. Michelin. 



Stomechinus Caumonti, Besor. Synopsis des Echinides Fossiles, p. 128. 



Test sub-conoidal, inflated at the sides ; ambulacra with four rows of tubercles, the 

 two internal rows short and less regular; inter-ambulacra with from eight to ten 

 rows of tubercles at the circumference, which diminish little in size at the upper surface ; 

 mouth opening very large. "This species is found to be one of the most characteristic of 

 the Bathonien stage." Besor. 



Formation. — " Marnes a Ostrea acuminata (Vesulien) de Herznach (Argovie). 

 Kellovien de Chatillon-sur-Seine." 



Collections. — " Hebert, Maesch, Mus. Zurich. Assez abondante." Besor. 



