220 NEW YORK STATE MUSEUM 



PLATE 8 



(All originals in the state museum) 



Thoracoceras wilsoni sp. nov. 



p. 126 



Fig. 



1-3 Three views of an internal cast ; ventral, lateral and dorsal. 

 This specimen retains the entire body chamber with aper- 

 ture and 17 septa; shows the strongly prismatic sides which 

 gradually become obscured over the body chamber, the 

 broad inner flattening or impressed zone which is continued 

 to the aperture, the gentle constriction of the body whorl 

 and the lateral sinuosity of the aperture. 



4 A cross-section of the same specimen showing the angularity 



of the septajte portion, the relatively great breadth of the 

 impressed zone and the gentle concavity of all the sides. 



5 The exterior of a part of the body whorl of the same specimen 



from a gutta-percha squeeze, showing the sinuosity of the 

 aperture, the continuation of both vertical and transverse 

 ridges in an obscured condition with low nodes at their 

 intersection over this surface, and in addition thereto the 

 very fine concentric lineation of the shell. 



6 The exterior of another specimen obtained by the removal of 



the shell from the matrix by calcination, the drawing being 

 made from a gutta-percha squeeze. This covers mainly the 

 septate part of the shell, shows the annuli and vertical 

 ridges with their strongly nodose intersections. In other 

 specimens these nodes are seen to be at times acute and 

 spiniform. The specimen also shows the finer concentric 

 lineation of the surface. 

 Agoniatites limestone. Manlius N. Y. 



