234 THE CHICAGO ACADEMY OF SCIENCES. 



separately. Glabella broad, with a large, often tumid .central 

 lobe, and from one to three side lobes. Eyes not large. Thorax 

 with nine or ten segments, and grooved and falcate pleura. 

 Pygidium large, flat, commonly with toothed or notched margin 

 corresponding to the pleural grooves; doublure very broad." 

 Beecher, Zittel-Eastman Text Book of Paleontology, p. 632. 



In' the subdivision of the family Lichadidce into generic 

 groups, the work of F. R. Cowper Reed " Notes on the Genus 

 Lichas" (Quart. Jour. Geol. Soc. London, vol. 58, pp. 59-82, 1902), 

 has been followed in the main, although his subgeneric divisions 

 are given generic rank. 



Genus 7. CORYDOCEPHALUS Corda, 1847. 



Cephalon broadly sub- triangular in outline, studded with 

 tubercles, spinules or spines. Glabella well denned by the dorsal 

 furrows, the median lobe protuberant in front and extending 

 backward to the occipital furrow, second pair of lateral furrows 

 obsolete, in consequence of which the first and second lateral 

 glabellar lobes are confluent and form a single pair of large com- 

 pound lobes, third pair of lateral glabellar lobes well defined, 

 lying between the large compound anterior lobes and the oc- 

 cipital furrow, behind these are a pair of basal or occipital lobes ; 

 cheeks broad, produced into a pair of curved genal spines which 

 proceed from the sides outward and backward, the post-cephalic 

 margin curving forward laterally to the bases of the spines. 

 Pygidium with a thickened marginal border; axis strongly de- 

 fined, elevated, connected with the marginal -border posteriorly 

 by a narrow post-axial ridge; the pleura with two segments, 

 each of which is produced laterally into more or less elongate 

 backwardly curving spines, the spines being produced across the 

 surface of the pleura to the axis as strongly raised ridges. 

 Corydocephalus phlyctainodes (Green), pi. xxu, figs. 1-4. 



Description. Cephalon, when viewed from above, semi- 

 elliptical or obscurely sub-triangular in outline, very convex, 

 strongly protuberant in front, deeply furrowed and covered 

 with tubercles and spines. Dorsal furrows deep and strong 

 anteriorly, becoming shallower behind, describing a convex 

 curve from the frontal margin to the outer extremities of the 

 third lateral furrows, then continued in a second convex curve 

 around the extremities of the third lateral lobes, and a third 

 slightly convex curve around the occipital lobes to the occipital 

 furrow. Glabella sub-circular or broadly sub-ovate in outline, 



