THE NATURAL HISTORY SURVEY. 277 



obsolete externally or connected with the dorsal furrows with 

 faint depressions; third lateral furrows similar to the second 

 except that they are continuous to the dorsal furrows with their 

 full depth. Occipital furrow continuous across the posterior 

 margin of the glabella, most deeply impressed toward its lateral 

 extremities. Occipital segment with nearly parallel anterior 

 and posterior margins, its width a little greater than the glabella 

 at its posterior margin. Cheeks sub-triangular in outline with 

 a marginal border of moderate width which is continuous around 

 the anterior extremity of the glabella, and from which the 

 anterior median spine-like extension is produced. Anterior 

 limbs of the facial sutures passing forward from the anterior 

 extremities of the eyes close along the outer margins of the 

 dorsal furrows, then crossing the dorsal furrows opposite the 

 lateral extremities of the frontal lobe of the glabella and con- 

 tinuing around the anterior margin of the glabella close to the 

 anterior edge of the frontal lobe; posterior limbs of the facial 

 sutures not well shown in the specimens. Surface of the 

 palpebral lobes sloping abruptly upward from the dorsal furrows 

 with the outer border bent still more abruptly upward, so bring- 

 ing the inner margin of the eye far above the level of the glabella. 

 Eyes large, their outer margins describing a little more than a 

 semi-circle, the faceted surface nearly vertical, separated ex- 

 teriorly from the cheeks by an undercut furrow, the entire surface 

 elevated above the surface of the glabella. The surface of the 

 cheeks is most prominent anteriorly from the eyes, they slope 

 away from the base of the eyes, laterally and anteriorly, rather 

 abruptly to the lateral cheek furrows which are well denned, 

 then after this interruption they continue their abrupt slope to 

 the margin, becoming less abrupt anteriorly; posteriorly each 

 cheek is marked by a marginal furrow which is continuous 

 behind the eyes with the occipital furrow, and joins the lateral 

 cheek furrows at their outer extremities; the genal angles are 

 produced posteriorly into spines of moderate length. 



Pygidium sub-triangular in outline, rather strongly convex, 

 mucronate posteriorly but not produced into an elongate caudal 

 spine; the axis well denned, about one-third the width of the 

 pygidium anteriorly, divided into eleven segments by trans- 

 verse furrows which, in the casts, are deeply impressed laterally 

 becoming much shallower across the median portion of the 

 axis; pleural lobes flattened within, sloping rather abruptly 

 at the sides to the lateral margins, without a flattened marginal 

 border, divided into about nine grooved segments which d^ 



