76 Field Museum of Natural History — Geology, Vol. IV. 



surround, leaving a narrow anterior border. In each furrow just in 

 front of the anterior glabella furrow is a distinct pit. Cheeks large, 

 sloping anteriorly and laterally from the eyes; posterior cheek furrows 

 narrow ; near the genal angles they meet the lateral furrows, which are 

 wider and extend forward parallel to the margins until they meet the 

 dorsal furrows; marginal borders somewhat concave on account of 

 shallow marginal furrows, which originate on the genal spines. Eyes of 

 moderate size, situated opposite the second glabella furrows, visual 

 surface sublunate, palpebral lobes moderately prominent, approaching 

 in height that of the glabella. The facial sutures originate a short dis- 

 tance in front of the genal angles, curve obliquely forward, then abruptly 

 inward to the posterior angles of the eyes, follow the inner margin of the 

 eyes and again forward with a broad curve, cutting the anterior margin 

 of the cephalon in front of the glabella (PI. XVII, fig. 8.) 



Thorax somewhat longer than wide, consisting of eleven segments, 

 distinctly trilobed. Axis narrower than the pleura?, regularly arched 

 upward. Pleural lobes flattened for about one-third their width, thence 

 abruptly curved to their lateral margins; each segment marked by a 

 deep groove across the axis; another smaller groove originates on the 

 anterior margin of each pleura near the dorsal furrows and crosses the 

 pleura obliquely; on the anterior margin of each pleura, near the point 

 where the pleura is bent downward, a still smaller groove defines a low 

 oblong node which points forward, not upward. The segments are 

 nearly transverse across the axis and about half the length of the 

 pleurae; their distal portions curve gently backward to the falcate 

 extremities. 



Pygidium small, transversely subelliptical, width more than twice 

 the length, posterior curve much flattened. Axis small with three well 

 defined annulations. Two shallow pits occur just back of the termina- 

 tion of the axis. Pleural lobes large, composed of three segments which 

 are produced posteriorly into flattened spines. The anterior pair is the 

 largest; carinate on top, strongly curved backward and obtusely rounded 

 at the extremities; the other two pair decrease in size inward and are 

 more pointed. 



Remarks. — Of the specimens here figured and described, figs. 6 and 

 7, are two views of an enrolled individual, complete with the exception 

 of the genal spines, in the collection of Mr. A. G. Becker, from the Lower 

 Maquoketa shale, Clermont; while figs. 8 and g (Mus. No. P 11130) show 

 specimens collected by the writer in the top of the Lower Maquoketa beds 

 at Clermont. In fig. 8 the position of the facial suture and the angle 

 formed by the posterior margin of the cephalon and the genal angles are 

 well illustrated. In Meek's original figure this angle is shown as a 



