448 A. W. GPvABAU THE SHERBUR^'E SA^-DSTOXE 



84. Pterinea (Vertumnia) repralia Hall 



This, too, seems to be a derivative of the Hamilton Pterinopecten 

 of the vertumnus type, or it may be a modification of the pre- 

 ceding form, ■ 



85. Pterinopecten erectus Hall 



This is likewise a derivative of the Hamilton species, probably 

 P. vertumnus, with which the young seems to agree. 



SQ. Pterinopecten suhorhicnlaris Hall 



Derived from one of the niimerons Hamilton species of the 

 genns. 



88. Ptychodesma nanum Hall 



The related Hamilton species is P. liiappianum Hall. 



89. Schizodus cliemungensw Conrad 



This, as Hall suggests, is closely related to S. cippressus of the 

 Hamilton, being '^probably only a variety of that species, which 

 lived under different conditions. ^^ 



90. S. chemungejisis var. quadrangularis Hall 



A modification of the preceding. 



Gastropoda 



92. Belleroplion explanatiis Hall 



Possibly a Hamilton form or derived from such a form as 

 B. natator. 



93. B. itliacaen,sis Kindle 



Affinities not ascertained. 



96. Euomphalus liecale Hall 



Seems to be most nearly related to E. mops of the Schoharie. 



101. Porcellia nais Hall 



Probably a derivative of the Hamilton (Delaware limestone) 

 species, P. liertzeri Hall. 



