236 THE CHICAGO ACADEMY OF SCIENCES. 



palpebral lobes. Eyes small, situated opposite the outer ex- 

 tremities of the third lateral lobes of the glabella, beneath the 

 bases of the spines which surmount these lobes. Surface of the 

 test thickly set with tubercles or short spines and by a smaller 

 number of long spines which are themselves covered with tu- 

 bercles. The most conspicuous of these spines are the two which 

 extend forward from the anterior surface of the median glabellar 

 lobe and the two which surmount the outer extremities of the 

 third lateral lobes of the glabella; two somewhat smaller spines 

 arise from the dorsal surface of the median glabellar lobe, and 

 three from the posterior border of the occipital segment; these 

 spines have usually been broken off but their bases may always 

 be detected. Free cheeks not known. 



Pygidium sub-semicircular in outline, with four long, 

 marginal, tuberculate spines. The axis large and convex, 

 narrowly sub-semielliptical in outline, with two annulations 

 'anteriorly, the first of which extends across the pleural slopes ; 

 occupying more than one-third the width of the pygidium an- 

 teriorly, the sides convex and converging posteriorly, the 

 posterior extremity reaching nearly to the marginal border and 

 .connected with it by a narrow and short post-axial ridge. The 

 pleural surfaces divided into two grooved segments, the pos- 

 terior element of each segment being much elevated in a broadly 

 rounded ridge extending from the dorsal furrow to the margin, 

 and then being produced into one of the long, rounded, tapering, 

 tuberculate spines which are longer than the body of the pygid- 

 ium itself; the anterior pair of spines have a strong backward 

 curvature until at their extremities they point in a posterior 

 direction, the posterior pair are less strongly curved, from the 

 margin of the pygidium they first diverge slightly, gradually 

 curving until in their posterior half they slightly converge. The 

 margin of the pygidium between the bases of the spines is 

 differentiated as a broad, thickened, convex, marginal border. 



The dimensions of a nearly perfect but rather small crani- 

 dium are: length 23 mm., greatest width 24 mm., convexity 

 10 mm. The dimensions of a pygidium are length 15 mm., 

 width 22.5 mm., approximate length of spines 20 mm. 



Remarks. This species is a close ally of the Bohemian C. 

 palmata Barr., but the cephalon of that species is not provided 

 with the large spines of the American form, and the shape of the 

 head is also different. The pygidia of the two species are also 

 quite different, the four spines of the American species being much 

 more elongate than the corresponding spines of the Bohemian 



