PI.ATK LVn— Continued. 



CaMAROTcECHIA (?) UUPUCATA, Hull. 

 FtCB. M-38. Ventral, frontal an<l iloreal views of the original example ; showing' the single plication and 



culcuB on sinus ami fold reai^eclively, and the obscure and sitarse lateral iilication. 

 Vig. 89. The interior of a lirachial valve, drawn from a gutta-percha cast ; showing the hinge-plate, crura, 

 median septum and muscular impi-essions, and also the thickening of the shell in the umhonal 

 region. X 3. 



Chemung group. CaUaratigiu couiUy, N. Y. 



Camakot<echia DoTi.s, Hall. 

 Figa. 40, 41. Ventral and profile views of a specimen of rather broad form, with rounded plications. 

 Hamilton group. Eighteen-Mile Creek, N. Y. 



CaMAKOT(K0HIA I'KOLIFICA, Hall. 

 Piga. 42, 43. Dorsal views of two internal casts ; showing slight differences in the degree of ite plication. 

 Hamilton group. Schoharie and Otsego counties, N. Y. 



Camarot(echia eximia, Hall. 

 Figs. 44, 4?). Cardinal and dorsal views of an intei-nal cast. 

 Chemung group. ItJiaca, N. Y. 



Ca]>iai{ot(echia orbicularis, Hall. 



Fig. 46. An internal cast of a brachial valve ; showing the cast of the spondylium. 



Fig. 47. Cardinal view of an internal cast ; showing the filling of the rostral cavity and the extent of the 



thickened median septum. 

 Fig. 48. An internal cast of the iiedicle-valve ; showing the adductor and diductor muscles and the ovarian 



markings. 

 Fig. 50. An enlargement of a i>ortion of the interior of the pedicle-valve ; showing the detailed structure 



of the muscular impression. 



Chemung gfroup. Meadtnlh, Pennsylvania. 



Camarotcechia contracta, Hall. 

 Fig. 49. An internal cast of the pedicle-valve ; showing the form of the muscular area. (See figs. 28-32.) 

 Hamilton gi-oup. Near Cardiff, N. Y. 



C'AMAR0T(ECHIA, sp. ? 

 Figs. 61-58. Ventral, profile and dorsal views of an internal cast in chert. 

 Burlington limestone. Burlington, Iowa. 



Camaroixechia, sp. indet. 

 Fig. 54. Cardinal view of an exti'emeiy gibbous intei-nal cast ; showing the Slling of the muscular cavity 

 in the pedicle-valve and the spondylium in the brachial valve, the cavities left by the dental 

 plates, hinge-plate, crura and median septum. 

 Waverly group. Ohio. 



