300 NORTH AMERICAN INDEX FOSSILS. 



curved, and connected with the neck furrow. In other respects 

 it differs from P. rowi in its smaller and more posteriorly placed 

 eyes and longer and narrower pygidium (average size of pygid- 

 ium is lo mm. in length by 13 mm. in width). Surface of glabella 

 and pygidium finely papillose. 



Upper Siluric (Decker Ferry) of New Jersey. 



113. P. protuberans Hall. Devonic. 

 Entire middle lobe of body very prominent. Glabella tapering 



forward, not distinctly lobed. Cheeks sloping abruptly from the 

 prominent eyes to the outer margin. Genal angles subacute. Neck 

 ring and furrow strong; occipital lobe small. Pleura abruptly 

 bent downward near their ends. Pygidium semicircular, its axis 

 with about eight annulations, the lateral lobes with four or five 

 ribs. Surface granulose. 



Lower Devonic (Coeymans) of New York, New Jersey and 

 Oklahoma. 



114. P. latimarginatus Hall. Devonic. 

 Differs from P. rowi in its narrower form, less tapering glabella, 



much shorter palpebral lobes ; cephalon with a broad, flat margin ; 

 three pairs of obscure lateral furrows present on glabella. 

 Middle Devonic (Schoharie grit) of Indiana. 



115. P. cras^imarginatus Hall. (Fig. 1611.) Devonic. 



Fig. 161 1. Proetus crassiniarginatus. (After Hall, 



Genal spines broad and flat. Glabella large, very convex, sub- 

 quadrate; no external evidence of glabellar furrows; neck ring 

 broad upon the axis, narrowing upon the cheeks. Pygidium 

 equally trilobate. 



Onondaga of New York, Ohio and Ontario. 



