174 



NEW YORK STATE MUSEUM 

 PLATE 16 



Cyrtoceras arcticameratum Hall 



(See plate 15, fig. i, 2) 

 Page 8 ' 



1-4 Four views of the most complete specimen observed ; showing 



the degree of curvature and rate of expansion of the conch 



5 Septum of a specimen, showing the marginal position of the 



siphuncle and a subcircular section 



6, 7 Two sections of another specimen with longer dorsoventral 

 axis 



Cyrtoceras bovinum sp. nov. 



(See plate 18, fig. 5, 6) 

 Page go 



8, 9 Two views of a specimen, showing the rapid expansion of the 



shell, depth of camerae and surface characters 

 All figures are drawn natural size, and are from Rochester 

 (Arey collection). 



