194 



NEW YORK STATE MUSEUM 



a single plication in sinus of pedicle valve and two on fold of 

 brachial valve; few plications on either side of fold or sinus. 



Pig. 108 Caniarotoecliia acinus. A specimen in which the fold and sinus are not developed. En- 

 lai'^ed X 4 



Found in the crystalline upper Clinton limestone at Niagara. 

 The species was originally described from the western Niagara. 



Genus rhynchonella Fischer de Waldheim 

 [Ety. : puyxo?, beak] 

 (1809. Notice dcs fos. goitv. Moscozv. p. 35; Hall & Clarke. 1893. 

 Pal. N. Y. V. 8, pt 2, p. 177, 178) 



Subpyramidal plicated shells with a prominent anterior linguiform 

 extension. Dental lamellae and a dorsal median septum occur, but 

 no cardinal process; crura are present, but other arm supports are 

 wanting. 



Ehynchonella robusta Hall (Fig. 109). 



Atrypa robusta Hall . (1852. PaL 

 N. Y. 2:71, pi. 23) 



Distinguishing characters. Large size; ro- 

 bust character; brachial valve most convex; 

 broad, ill defined fold and sinus; coarse 



Fig. 109 Rhynchonella robusta j-QUnded plicatiOHS. 



Found in the uppermost beds of the Clinton series at Niagara. 

 Also east of Lockport (Hall). 



Ehynchonella (?) bidens Hall (Fig. no). 

 Atrypa bidens Flail (1852, Pal. N. Y. 

 2:69, pi. 23) 



Distinguishing characters. Much smaller than 

 preceding-; stronp- convexity of valves; deep sinus 



^ &' fe : '1 Fig. 110 Rhynchonella 



with one plication; fold consisting of two rounded ^'^^"^^'^^ 

 plications; rather broad, rounded lateral plicae; strongly emarginate 

 front. 



Found in the lower Clinton beds at Lockport (Hall). Probably 

 also at Niagara. 



