PLATE LXXXI— Continued. 



V\g. 31. Dorsal view of an internal cast of a narrow and elongate shell, in which the impression of the 



mii8(;ular platform of the brachial valve is sharply defined. 

 Vlg. 33. A gutta-percha iinpre.«sion made from the same specimen ; showing the collar or inverted lamella 

 about the foramen, a portion of the dental plates and the form of the muscular platform. 

 Upper Carbonifei-ou8 limestone. Soutliera Indiana. 

 Figo. SS-S.*!. Profile, dorsal and ventral views of a large and characteristic example ; showing the curvature 

 of the valves, the broml concavity of the pedicle-valve and the reflexion of the anterior mar- 

 gins ; also the oblique forarainal apei-ture. 



Upper Carbonifei-ons limestone. Harrison county, Missouri. 



DiELASMA, .sp. ? 



Pig. 345. Canlini^ view of a specimen enlargerl to show the oblique opening of the pedicle-passage and its 



cross-striated sui'fa<te. X 3. 

 Kjf. 37. An internal cast of the bi-achial valve ; showing the form and striation of the muscular platform. 



X3. 



Chester group. Oalduoell county, Kentucky. 



DiELASHA OBOVATA, Sp. IIOV. 



Rgs. 38-40. Dorsal, profile and ventral views of a specimen having the aspect of D. fomwsa, but said to be 

 from the Coal Measures. 



Coal Measures. Kentucky. 



Genus CRYPTONELLA, Hall. 



Page 38fi. 



CrYPTONELLA SUBELLIPTICA, sp. llOV. 



Figs. 41-43. Dorsal, profile and ventral views of a large internal cast in iron-stone ; showing the form, con- 

 tour and muscular scara of the brachial valve. 

 Waverly grouj). l^<w4uinUe, Ohio. 



