274 THE CHICAGO ACADEMY OF SCIENCES. 



and cutting the lateral margins a little back of a line through 

 the centers of the eyes. Inner surface of the palpebral lobes 

 sloping gently upward from the dorsal furrows, the outer margins 

 bent abruptly upward^ to the facial sutures at the inner borders 

 of the eyes. Eyes large, sub-crescentiform, their length a little 

 more" than, half the length of the glabella along its median line, 

 the height of the faceted portion a little less than one-half 

 their length ; the' faceted portion nearly vertical posteriorly but 

 gradually sloping inward more and more to the anterior extrem- 

 ity where the slope is nearly forty-five degrees. Laterally 

 from the eyes the surface of the cheeks is gently convex to the 

 marginal furrows, the marginal border is rather broad and 

 flattened anteriorly, becoming obsolete back of a line passing 

 through the posterior extremities of the eyes in the extension 

 of the cheeks into the genal spines. The posterior cheek furrows 

 are continuous from the dorsal furrows nearly to the lateral 

 margins, laterally they curve backward but are not confluent 

 with the lateral cheek furrows. 



Thorax with eleven segments; the axis strongly defined, 

 moderately convex, occupying less than one-third the entire 

 width; pleural lobes flattened on top for more than one-half 

 their width and then curving rather abruptly downward to the 

 lateral margins ; the pleura conspicuously grooved longitudinally, 

 the grooves nearly bisecting each segment from the dorsal 

 furrow .to the point where they bend downward, then curving 

 backward and becoming obsolete before reaching the extrem- 

 ities of the segments. 



Pygidium sub-triangular in outline, with a long, slender, 

 flattened caudal spine whose length is more than one-half the 

 total length of, the pygidium. Axis well defined, depressed- 

 convex, occupying less than one-third the width of the pygidium 

 anteriorly, tapering posteriorly and terminating within the 

 proximal extremity of the caudal spine, divided into twelve 

 segments by transverse furrows which are deeply impressed 

 laterally in the internal casts but are much fainter across the 

 median portion of the axis. The pleural lobes are flattened 

 for more than half their width from the furrows, and then 

 slope rather abruptly to the lateral margins, they are divided 

 into eight grooved segments which -curve backward distally 

 and become obsolete just within the lateral margin, posteriorly 

 the segments become much fainter, the last one or two sometimes 

 being scarcely distinguishable. 



