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. 



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

 larged x i 



Found in the crystalline upper Clinton limestone at Niagara. 

 The species was originally described from the western Niagara. 



Genus rhynchonella Fischer de Waldheim 



[Ety. : puyxos, beak] 



(1809. Notice des fos. gouv. Moscow, 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. 



Khynehonella robusta Hall (Fig. 109). 



A t r y p a 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 roun( J e( i plications. 



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

 Also east of Lockport (Hall). 



Rhynchonella (?) bidens Hall (Fig. no). r - ^ ,\,/ 



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

 2 169, pi. 23) 



Distinguishing characters. Much smaller than 

 preceding; strong convexitv of valves; deep sinus 



r ° & - r Fig. 1 10 Rhynchonella 



with one plication ; fold consisting of two rounded (?) bldens 

 plications; rather broad, rounded lateral plicae; strongly emarginate 

 front. 



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

 also at Niaeara. 



