GASTROPODA— BELLEROPHONTIDJE. 



625 



Hamilton of New York, Falls of the Ohio, Maryland, Virginia, 

 and Pennsylvania. 

 72. P. rudis (Hall). (Fig. 842.) Devonic. 



Differs in having slight median angulation and strong concen- 



FiG. 842. Ptomatis rudis, in different states of preservation, showing striae and strong 

 undulation, somewhat distorted. (Pal. N. Y., V.) 



trie rugae on last whorl ; radiating striae often seen between rugae. 

 Hamilton group of eastern New York, etc. 



XXIII. Phragmostoma Hall. (Emend. Clarke.) 

 Differs from Ptomatis in having a narrow, sharply defined slit- 

 band, callus of inner lip thick, flattened, and wedge-shaped, but 

 does not form a true septum as in Carinaropsis. Devonic. 



W9 



Fig. 843. Phragmostoma natator. (After Clarke.) 



73. P. natator Hall. (Fig. 843.) Devonic. 

 Abruptly expanding lip, narrow deep sinus, surface with growth 



lines and wrinkles only. 



Portage (Naples) beds of New York, etc. 



74. P. chautauquae Clarke. (Fig. 844.) Devonic. 

 With more strongly pronounced narrower young whorls longi- 

 tudinally striate, smooth in adult, with narrow, sharp slit-band, and 

 abruptly expanding lip. 



Portage (Naples) of New York. 



