398 A. HYATT — GEOLOGY OF THE TAYLORVILLE REGION. 



Hemientolium daytonensis, n. g., very rare. 

 Modiola triqusetrseformis, n. sp.,well represented. 

 Avicula mucronata, Gabb, common. 

 Inoceramus (?) gervillioides, n. sp., rare. 

 /V/7m/ inexpectans, n. sp.. well represented. 

 Lirao acwfo, n. sp., well represented. 



This fauna therefore contains all of the species found in the Monotis 

 bed below, but Monotis lias become very rare, while Modiola is well rep- 

 resented. Among the remaining specie-. Daonella alone is peculiar to 

 this level, and Avicula mucronata is characteristic, 1 icing found here as a 

 common fossil, while both above and below this it is rare, and in the 

 limestone it is, as a rule, smaller and of a different variety. Inoceramus 

 gervilliodes is also characteristic of this level. 



Rhabdoceras Bed. — Immediately above the slates is a narrow band of 

 limestone containing an abundant fauna which, however, could not be 

 exhaustively explored on account of the fragmentary character and 

 small extent of the superficial outcrops. It comprises — 



Monotis subcirctdaris, Gabb, very rare. 



Avicula mucronata, Gabb, very rare. 



Pert i a ilt form is, Gabb, very rare. 



Pecten lasseni, n. sp.. well represented. 



Modiola triqusetrseformis, n. sp., well represented. 



Myacites, n. sp.. common. 



Nucula tin hi*, n. sp., common. 



Lima acuta, n. sp.. well represented. 



Li inn. sp. (?), a large, almost smooth cast. 



Ostrsea, sp. (?), one imperfect valve. 



Inoceramus (?) simplex, n. sp.. rare. 



Rhynchonella solitaria, n. sp. 



Arcestes californiensis, n. sp., common. 



Halorites americanus, rare. 



Ammonites ramsaueri, Gabb, rare. 



Rhabdoceras russelli* n. sp., rare. 



Atractites, sp. (?), well represented. 



The fauna, of the limestone differs markedly from that of the upper 

 slates and still more from the lower slates. It lias all the species men- 

 tioned as occurring below, but they are all rare except Modiola, Pecten 

 lasseni&nd Lima acuta. As additions we find to he abundant Myacites 

 and Nucula, with a Large Lima, an Ostrsea and a Rhynchonella. There arc 



♦Dedicated to Mi-. I. C. Russell in memory of our work in the field. 



