LOWER SILURIAN. 



205 



2. Mollusks. — The Trenton Brachiopods Leptcena sericea Sow., Fig. 331; Stro- 

 phomena alternata Con., Fig. 333; Orthis testudinaria Dalm., Fig. 329; Orthis lynx 

 Eichw., Fig. 32G; Orthis occidcntalis H., Fig. 328; Rhynchonella capax Con., Figs. 334- 

 336; and some others, are continued in the Cincinnati epoch; also the Heteropod 

 Bellerophon bilobatus, Figs. 348, 349 ; the Gasteropod, Murchisonia bicincta H. ; the 



Fig. 375. 



Echinoderm — Palasterina (?) Jamesii. 



Cephalopods, Trocholltes Ammonivs Con., Fig 358, and species of the Orthoceras family, 

 etc. The following are characteristic species: Lamellibranchs, Pterinea demissa M'Coy, 



Lamelubeanchs. — Fig. 376, Pterinea demissa ; 377, Ambonychia radiata ; 378, Modiolopsis 

 modiolaris (X%) ; 379, Orthonota parallela. 



Fig. 376; Ambonychia radiata H., Fig. 377; Modiolopsis modiohris Con., Fig. 378; 

 Orthonota parallel! H., Fig. 379 ; Cyrtodonta Hindi B. ; Dolabra Sterlinaensu M. & W., 



