56 PALAEONTOLOGY OF NEW YORK. 



deep; third lateral lobes well-defined, transverse. Occipital furrow narrow, 

 becoming wide and deep upon the cheeks; occipital ring very wide upon 

 the axial line, but narrowing to the axial Furrows and upon the cheeks. 



Cheeks elevated, very convex and protuberant at the sides, constricted at 

 their bases by the broad marginal sulcus; posterior slope abrupt. The 

 summit about the base of the eye is grooved by a deep orbital sulcus. 



Eyes lunate elevated, moderately large; palpebrum depressed; lenses 

 abundant. 



Thorax and Pygidium unknown. 



Surface covered with conspicuous, often sharp, spiniform tubercles, of 

 which the strongest appear to be one in each angle of the occipital ring and 

 marginal sulcus, and a single row about the bases of the marginal denticula- 

 tions. Upon these processes the ornamentation consists of fine granules. 



Dimensions. The more perfect example of the cepbalon has an axial length 

 of 45 mm.; a length to the extremity of the cheek spines of 92 mm., and 

 a width of 88 mm. 



Observations. All that is known of this remarkable species is from the two 

 somewhat fragmentary cephala which were collected in the year 1832. One 

 of these is a cast of the dorsal surface and the other preserves nearly the 

 whole of the crust. In the peculiar denticulate character of the border, distinct 

 from that in the sub-genus Odontocephalus, the species finds an ally in the 

 minute Dahnanites pygmmis of the Corniferous limestone. 



Distribution. Upper Helderberg group. Schoharie grit, in the town of Knox, 

 Albany county. 



DALMANITES (CORYCEPHAL0S) PYGJ.LEUS, 11. Sp. 

 PLATE XI. FIGS. 5-8. 



CephalON minute, outline sub-semicircular or sub-elliptical. Surface convex, 

 abruptly depressed at the sides. Margin narrow, thickened and produced 

 at the genal angles into long slender spines which curve inward toward the 

 extremity. 



