NIAGARA FALLS AND VICINITY I93 



median septum in the brachial valve, which divides posteriorly, so 

 far as to form an elongate cavity, which does not extend to the bot- 

 tom of the valve. No cardinal process. In the pedicle valve slen- 

 der vertical lamellae support the teeth. 



Camarotoechia obtusiplicata Hall (Fig. io6). Atrypa ob- 

 t u s 1 p 1 i c a t a Hall (1852. Pal N. Y. 2 1279, pi. 58, fig. 2a-h) 



Disfinguishiiig characters. Ciibbous, subspheroidal form; strongly 

 convex brachial, and flatter pedicle valve; deep sinus of pedicle 



Fig. 106 Camarotoecliia obtusiplicata 



valve with three plications (rarely four) ; depressed incurved beak of 

 pedicle valve; simple, obtusely rounded or flattened plications; faint 

 concentric striae; strongly emarginate front. 



Found in the lower part of the lower Rochester shales at Niagara. 

 Also in the shales and limestones at Lockport (Hall). 



Camarotoechia ( ?) neglecta Hall (Fig. 107). Atrypa 

 neglect a Hall (1852. Pal. N. Y. 2:70, 274, pi. 23 and 57) 



Distinguishing characters. Convex 

 valves, brachial valve deepest, sides 

 sloping abruptly to the beak; strongly 

 defined sinus and fold, in adult individ- 

 ual, the former wath three, the latter 

 with four plications; profound frontal 

 emargination; plications rounded. 



Found in the lower Clinton limestone 



Fig. 107 Camarotoechia (?) neglecta 



m the Clmton lenses and ni the upper 



part of the low^er and the middle Rochester shales at Niagara. 

 Also more rarely in the upper shales. Found also at Lockport and 

 elsewhere (Hall). 



Camarotoechia acinus Hall (Fig. 108). R h y n c h o n e 1 1 a 

 acinus Hall (A^. Y. state miis. nat. hist. 28th an. rep't, p. 163, 

 pi. 26) 



Distinguishing characters. Small size; longitudmally ovate form, 

 narrowing toward beak, truncate in front; subequally convex valves; 



