PLATE XV. 



PAGE 



JFig. 21. Ptychoceras quadratus. 74 



Natural size. 



Tig. 25. Crioceras latus. 76 



$ Natural size. 

 a. Section of volution. 



Fig. 30. Anuyloceras. Sp. indet. 78 



3 Natural size. 

 a. Septum. 



