Pr-ATK LVn— Continued. 



CaMAROTCECHIA (?) DUPLICATA, Hall. 

 Fig-s. 36-38. Ventral, frontal and dorsal views of the original example ; showing the single plication and 



sulcus on siiuis ami told respectively, and the obscure and sparse lateral plication. 

 Fii>-. 3y. The interior of a brachial valve, ilrawn from a gutta-percha cast ; showing the hinge-plate, crura, 

 median septum and muscular impressions, an<l also the thickeTiing of the shell in the umbonal 

 region. X 2. 



Chemung group. Cattaraugus county, N. Y. 



C'amahotiechia Doris, Hall. 



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

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



CaMAKOT(ECHIA PKOLIFICA, Hall. 

 Figs. 42, 43. D(u-sal views of two internal ca.sts ; showing slight differences in the degree of its plication. 

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



Camarot(J':chia eximia, Hall. 



Figs. 44, 4n. Cardinal and dorsal views of an internal cast. 

 Chemung group. Ithaca. N. Y. 



Cajiakotcechia 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 pedicle-valve ; showing the adductor and diductor muscles and the ovarian 



markings. 

 Fig. 50. An enlargement of a poi-tion of the interior of the pedicle-valve ; showing the detailed structure 



of the muscular impression. 



Chemung group. Meadi'ille, Pennsylvania. 



( "AMAROTUiCHIA CONTKACTA. Hall. 

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

 Hamilton group. Near Cardiff, N. Y. 



C'aMAROTCECHIA, SJ). ? 

 Figs. 51-53. Ventral, profile and dorsal views of an internal cast in chei-t. 

 Burlington limestone. Burlingto^i, lo^oa. 



Camarotcechia. s[). iiiilet. 

 Fig. 54. Cardinal view of an extremely gibbous internal cast ; showing the filling 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. 



