228 THE CHICAGO ACADEMY OF SCIENCES. 



segments usually ten, with grooved pleura. Pygidium large, 

 semi-circular, with a thickened marginal border, the axis well 

 defined by the dorsal furrows, strongly elevated, distinctly 

 segmented, and extending to the inner side of the marginal 

 border, the pleural segments grooved. 

 Proetus channahonensis n. sp., pi. xx, figs. 6-7. 



Description. Head moderately convex, semi-circular in 

 outline, the length of the genal spines not determined. Glabella 

 semi-elliptical in outline, depressed convex, denned by distinct 

 but not deep dorsal furrows; first and second lateral furrows 

 obsolete or faint, nearly transverse in direction and not con- 

 tinuous across the median portion of the glabella, posterior 

 furrows not deeply impressed but always present, they originate 

 at the dorsal furrows opposite the eyes and extend obliquely 

 inward and backward with a slight convex curve nearly to the 

 occipital furrow, their posterior extremities dividing the glabella 

 into three nearly equal parts. Occipital furrow narrow, well- 

 defined, including a pair of small subovate occipital lobes back 

 of the postero-lateral angles of the glabella. Occipital segment 

 rather narrow, its surface somewhat depressed below the glabella. 

 Surface of the cheeks sloping with an even convex curve from 

 the dorsal furrows laterally and anteriorly to within about one 

 millimeter of the margin, outside this convex slope is an even,, 

 flattened, continuous marginal border which continues around 

 the anterior margin of the head; along the posterior margin of 

 each cheek is a strong posterior cheek furrow which is continuous 

 from the dorsal furrow opposite the occipital furrow to the inner 

 side of the marginal border. The anterior extremity of the 

 glabella is separated from the marginal border by a narrow 

 band which is continuous with the corrvex portion of the cheeks 

 on either side. The fixed cheeks are narrow with the palpebral 

 lobes rising directly from the dorsal furrows. Free cheeks 

 broad, the eyes of moderate size, their surface describing about 

 a semi-circle, 'their anterior extremities at about the mid-length 

 of the glabella. 



Pygidium semi-elliptical in outline, the axis strongly con- 

 vex, bordered by the sharp dorsal furrows, occupying nearly 

 one-third the entire width of the pygidium at the anterior mar- 

 gin, tapering posteriorly and terminating in a bluntly rounded 

 extremity lying within the marginal border, divided into ten 

 or eleven rounded annulations Vhich become faint posteriorly. 

 Surface of the pleura slightly flattened adjacent to the dorsal 



