PLATE L. 



Ctrtoceras Jason. 



Page 381. 



Fig. 1. A l^i-ge tngnwnt, preserving- the grand chamber and a portion of the air-chambers, showing the 

 curvatui-e of the tube and the depth of the air-chambers. Toward the apex there is a sinus in 

 several of the septal sutures, produced by the spinous processes of the test. 



Fig. 2. A fragment of a large individual, preserving the natural form of the shell, showing the hexangular 

 form of the tube and the sinus of the ornaments on the ventral side. Several fragments of the 

 test are pi-eserved, with the lamellose surface-markings. The interaal mould retains the 

 im]>i-e88ion of the furrows and strite of the crenulations, with the bases of the spines on 

 the obtuse angles of the tube. 

 The specimens of this species here illustrated are from the Schoharie grit, Schoharie, N. Y. 



