THE NATURAL HISTORY SURVEY. 243 



lateral angles of the cranidium, the posterior margins of the 

 free cheeks deeply sinuate; anterior and lateral margins de- 

 pressed in a flat marginal border which is narrowest in front 

 of the glabella. Glabella bordered by well-defined dorsal or 

 axial furrows; the median lobe prominent and abruptly elevated 

 in front, but not protuberant beyond the anterior cephalic 

 margin, very broad in front, becoming rapidly narrower poste- 

 riorly; the anterior lateral furrows deeply impressed, continuous 

 posteriorly with the third lateral furrows which curve outward 

 toward the eye-lobes and terminate somewhat abruptly, not 

 joining the occipital furrow; anterior lateral lobes compound, 

 elliptical in outline, strongly convex, their posterior extremi- 

 ties higher than the surface of the median lobe between; second 

 lateral furrows nearly obsolete, represented only by slight in- 

 dentations in the inner margins of the anterior lateral lobes 

 at about their mid-length ; third lateral lobes ill-defined, coalescent 

 with the anterior lobes externally in front, and partially coales- 

 cent with the median lobe internally. Occipital furrow well- 

 defined, nearly straight in its central part, broadening laterally 

 back of the third lateral glabellar lobes and including a pair of 

 small, depressed, sub-triangular, ill-defined occipital lobes. 

 Occipital segment convex, rather broad, becoming a little nar- 

 rower laterally. Fixed cheeks prominent in the region opposite 

 the eye-lobes, sloping abruptly to the front and somewhat less 

 abruptly, with a convex surface, postero-laterally back of the 

 eyes. Free cheeks large, depressed except near the eyes where 

 the surface is rather abruptly elevated to the outer margins 

 of the eyes, produced laterally opposite the eyes, into broad, 

 flat spines which curve outward and backward, the post-cephalic 

 margin curving forward to the bases of the spines. 



Pygidium sub-elliptical in outline, its surface depressed- 

 convex. Axis occupying more than one-third of the entire 

 width of the pygidium at its anterior margin, with a single dis- 

 tinct annulation anteriorly, bordered by distinct dorsal or axial 

 furrows which continue posteriorly and bound a broad post- 

 axial region which- is strongly contracted near the middle of 

 the pygidium and which is coalescent posteriorly with thepleural 

 segments on either side. The limb is divided into three pairs 

 of broad, deeply grooved segments, the general surface is gently 

 convex from the dorsal furrows through about one-half the 

 width to the lateral margins, beyond this becoming slightly 

 concave. The postero-lateral extremities of the two anterior 

 pairs of plemral segments are produced somewhat into back- 



