302 NORTH AMERICAN INDEX FOSSILS. 



Kinderhook (Louisiana limestone) of Missouri; Waverly of 

 Ohio. 



120. P. peroccidens Hall and Whitfield. Mississippic. 

 Differs from P. macrocephalus in its longer genal spines, its 



longer and narrower glabella, free from pustules. Pygidium ab- 

 ruptly convex at sides and posteriorly; its axis with pustules 

 arranged in four longitudinal rows. 

 Mississippic limestone of Utah. 



XLVII. Cyphaspis Burmeister. 

 Small, oval. Cephalon semicircular. Genal angles produced into 

 long spines. Glabella arched, short and narrow, bounded on all 

 sides by a deep furrow, and with two lobes attached to the base. 

 Cheeks broad and granulose. Eyes small and crescent-shaped. 

 Thorax with lo to 17 segments, which are all rounded at the ex- 

 tremities. Pygidium semicircular, with two to eight segments in 

 the axis. Ordovicic-Devonic. 



121. C. matutina Ruedemann. Ordovicic. 

 Glabella somewhat roundly quadrangular, moderately convex; 



the anterior two pairs of glabellar furrows faint and oblique, the 

 third semicircular, extending to the neck furrow and separating 

 the pair of less convex basal lobes. Entire surface of cephalon 

 smooth. Otherwise much like C. ornata. 



Rysedorph conglomerate of New York ; Chambersburg limestone 

 of Pennsylvania. 



122. C. trentonensis Weller. Ordovicic. 

 Differs from C. ornata in its minute size (length of cephalon 5 



mm. ; width at anterior end between facial sutures 4.5 mm. ; length 

 of glabella 3 mm.); relatively large basal lobes; glabella very 

 strongly arched both longitudinally and transversely; frontal 

 border narrow, smooth, bounded by a sharply impressed furrow; 

 between this furrow and the glabella the area (closely pitted) is 

 convex and slightly broader than the frontal border. Frontal 

 border smooth. Glabella and basal lobes tuberculate. 

 Trenton of New Jersey. 



123. C. ornata Hall. (Fig. 1614.) Devonic. 

 Frontal border with a single row of bead-like tubercles and a 



broad furrow between it and the glabella. 



Hamilton of New York, etc. « 



