172 



FIG. 



I 



NEW YORK STATE MUSEUM 

 PLATE 15 



* 



I 



17 ©O 



6 



r 



8 







10 



11 



Cyrtoceras arcticameratum Hall 



(See plate 16, fig. 1-7) 

 Page 87 



A specimen retaining the shell and exhibiting the character 

 of the surface 



2 A specimen with closely arranged septa 



Cyrtoceras orodes Billings 



Page 88 



3 Septal view of a specimen, showing the marginal position of 



the siphuncle and the difference in curvature between the 



inner and outer sides 

 4, 5 Two views of an internal cast, referred with some doubt to 



this species, showing a rapidly expanding living chamber 



and subcircular section 

 6-8 Three views of an internal cast, showing the depth of the 



camerae and direction of the sutures 

 9 A specimen exhibiting the siphuncle 



