238 THE CHICAGO ACADEMY OF SCIENCES. 



of the anterior or first with the third lateral glabellar furrows, 

 back of which point it is partially coalescent with the third 

 lateral lobes. Anterior lateral furrows deep and narrow, cle- 

 scribing a concave curve from their anterior point of origin to. 

 their junction with the third lateral furrows, beyond which 

 they are produced posteriorly to the occipital furrow as slight, 

 ill-defined depressions. Second pair of glabellar furrows obso- 

 lete. Anterior lateral lobes large, compound, formed by the 

 coalescence of the first and second pairs of lobes, strongly convex, 

 irregularly sub-elliptical in outline, the longer axes directed 

 obliquely forward. Third lateral furrows of the same depth and 

 size as the anterior ones and continuous with them, being 

 joined by a sharp curve; from this point to their junction with 

 the dorsal furrow they are straight and are directed obliquely 

 forward. Third lateral lobes quadrilateral in outline, length 

 and breadth nearly equal, not sharply separated from the 

 posterior portion of the median lobe, less than one-half the 

 size of the compound anterior lobes. Occipital furrow broad, 

 deep and straight across the posterior extremity of the median 

 glabellar lobe, dividing on each side, the two divisions on each 

 side bounding a pair of small, triangular occipital lobes situated 

 back of the outer portions of the third lateral glabellar lobes. 

 Occipital segment gently arched, broad in the center, becoming 

 narrower laterally. Fixed cheeks convex, sloping both an- 

 teriorly and posteriorly, the palpebral lobes rather large, -elevated, 

 semi-circular! Free cheeks convex, sloping rather abruptly 

 from the eyes, produced laterally from a point nearly opposite 

 the eyes into flattened spines which are directed obliquely 

 backward, and whose length is equal to about one-fourth of .the 

 width of the cephalon exclusive of the spines. The post-cephalic 

 margin curving forward to the bases of the lateral spines. 



Pygidium sub-semielliptical in outline; the axial portion 

 occupying a little more than, one-fourth of the entire width at 

 the anterior margin, strongly convex anteriorly with two narrow, 

 rounded annulations, back of which is a convex bulbous portion 

 which becomes depressed near the center of the pygidium ; back 

 of the elevated portion the two axial furrows which bound the 

 post-axial region converge to the posterior margin; the pleura 

 are nearly flat and are divided into three, broad, grooved seg- 

 ments, all of which are produced on the margin into short, free 

 points. The entire surface finely tuberculate. 



The approximate dimensions of a large cephalon are: 

 length 17 mm., width to ends of lateral spines 37.5 mm., width of 



