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NEW YORK STATE MUSEUM 

 PLATE 15 



Cyrtoceras arcticameratum Hall 



(See plate 16, fig. 1-7) 

 Page 87 



FIG. 



1 A specimen retaining the shell and exhibiting the character 



of the surface 



2 A specimen with closely arranged septa 



Cyrtoceras erodes 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 



