GUELPH FAUNA IN THE STATE OF NEW YORK 159 



FIG. 



15 Enlargement of part of a specimen with extremely coarse 



revolving and irregular transverse lamellose growth lines 

 on the last volution 



Poleumita crenulata Whiteaves (sp.) 



Pat'e 64 



9, 1 1 Two views of a young specimen, exhibiting very sharp sculp- 

 ture lines 



1 6 Apical view of a typical individual. From a gutta-percha 



squeeze of a natural cast. Lower Shelby bed (N. Y. State 

 Museum) 



17, 1 8 Two views of a specimen with very sharp, distant, transverse 

 lines, showing also the gradual suppression of the revolving 

 ridges upon mature volutions 



19 Enlargement of the sculpture on the basal side of a large 



individual, showing the coarse growth lines and the faint 

 revolving ridges. X3 



20 Individual retaining the revolving ridges upon the last 



volution 



21 A very large individual, showing distinct gerontic characters 



upon the last volution. From a gutta-percha squeeze of a 

 natural impression. Lower Shelby bed (N. Y. State 

 Museum) 



22 Natural section of the volutions 



23 Lateral view of an individual with depressed spire 



24 Apical view of a specimen, showing strong contrast between 



the ornament of the last and early volutions 

 All figures are natural size and all originals are from the 

 Guelph at Rochester, where not otherwise stated. 



