TRILOBITA—OPISTHOPARIA. 309 



side lobes more prominent posteriorly than anteriorly. Pygidium 

 with a very prominent axis, which extends about one third its 

 length and rises posteriorly into a rounded knob from which rise 

 two^strong spines ; the median lobe rises in the middle into a node 

 which bears two spines and then slopes backward and bifurcates; 

 each side lobe with three grooved pleura, each ending in a strong 

 mucronate process, the rounded sinuses between which extend 

 about one third the distance to the axis; the two posterior pleura 

 are straight, the anterior curving slightly backward. Entire sur- 

 face of test covered by strong pustules with some spines on the axis 

 and ribs of the pygidium. 



Helderbergian of New York and New Jersey. 



LIII. CoNOLiCHAS Dames. 



Glabella with median and one pair of lateral lobes; the median 

 and sometimes the lateral conically elevated, the elevations often 

 incHned backward. Ordovicic-Devonic. 



141. C. eriopis Hall. (Fig. 1620.) • Devonic. 



Fig. 1620. Conalichas eriopis, two pygidia. (After Hall and Clarkt. ) 



Median lobe of glabella elongate-pyriform, with anterior half 

 very convex ; side lobes very convex posteriorly. Eyes prominent, 

 crescent-shaped. Pygidium as shown in figure. Surface pustu- 

 lose, and with more or less regularly placed spines. 



Onondaga of New York. 



LIV. CoRYDOCEPHALUs Corda. 

 Cephalon crested with tubercles or spines. Glabella with middle 

 lobe protuberant in front and extending back to the neck furrow; 

 the first and second lateral lobes united, forming a single pair of 



