200 



PALEOZOIC TIME. 



nella groups, — the same families that were represented in the early 

 Calciferous epoch. The genera RhynchoneUa, which began in the era 



Figs. 326-340. 



Brachiopods — Figs. 326, 327, Orthis lynx ; 328, 0. occidentalis ; 329, 0. testudinaria ; 330, O. 

 tricenaria; 331, Leptsena sericea; 332, Strophomena (Leptaena) rugosa ; 333, Stroph. alternata; 

 334, 335, 336, Rbynchonella capax ; 337, 338, Rbyncbonella (?) bisulcata; 339, Obolus filosus ; 310, 

 Lingula quadrata. 



of the Quebec group, and Crania (Fig. 242), of the Trenton, have 

 representatives in modern seas. 



Orthocerata (Figs. 353-355), of the tribe of Cephalopods, were 

 very numerous, and some were ten to fifteen feet long. Fig. 353 rep- 



Lamellibranchs. — Fig. 341, Avicula(?) Trentonensis ; 342, Ambonychia bellistriata ; 343, Telli' 



nomya nasuta. 



resents a portion of one of these long conical (or straight horn- 

 shaped, as the name signifies, p. 187) shells, and exhibits the parti- 

 tions dividing it interiorly into chambers ; and, in Fig. 353 a. one of 



