CONTRIBUTIONS TO PALEONTOLOGY. 281" 



The Chonetes scitula, C. lepida and C. setigera occur likewise in the Che- 

 mung group, together with a remarkable species, the C. muricatus. 



The Chonetes logani was originally described from the base of the Bur- 

 lington limestone of Iowa ; and a careful comparison of specimens from 

 that locality, as well as from intermediate points in Ohio, together with 

 casts of the same, has left no doubt of the propriety of referring the 

 TuUy limestone species to that one. The criticisms of Prof Winchell 

 regarding the concentric lamellose lines or ridges, I do not regard as of 

 even varietal value, and the varying conditions in this respect are merely 

 accidental. The species is illustrated on Plate xxii of Vol. IV, Palcem- 

 tology of New York ; and every care has been taken to give a true 

 representation of the characters of specimens from Iowa, Ohio and New 

 York. 



Cab. Nat. 36 



