574 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxx. 



of the p3'gidium. These indicate that the general form of the head 

 was transversely semicircular, and rather strongl}^ convex, and that 

 the margin of the head was of medium ^ridth in front, gradual}}^ 

 widening to the free cheek, where it narrows toward the base of the 

 postero-lateral spine. A postero-lateral spine projects backward and 

 slightly upward from a point on the margin a little in advance of the 

 postero-lateral angle. Glabella truncato-conical in outline, and marked 

 by three pairs of furrows, the posterior of which extends obliquely 

 backward nearly to the occipital furrow; the anterior furrows are 

 indicated by short, slight depressions on the edges of the glabella next 

 to the dorsal furrow; they are situated so as to divide the space be- 

 tween the posterior furrows and the front margin of the glabella into 

 sube<|ual spaces; a very narrow, slightly indicated, median, longitudi 

 nal ridge extends from the occipital furrow nearl}' to the front of the 

 glabella; occipital furrow strongly marked, rounded, and about as 

 wide as the occipital segment; occipital segment of medium width, 

 convex, and arching forward slightly at the center; a shallow furrow 

 crosses it on each side so as to outline a rounded node at each end; 

 dorsal furrow rounded, rather strong at the ends, and merging into 

 the broad concave slope of the frontal limb. 



Plxed cheeks about one-half the width of the glabella; the}" rise 

 abruptl}^ from the dorsal furrow to the base of the palpebral lol)es, 

 and slope rapidly from the palpebral lobes backward to the posterior 

 furrow, and more rapidly to the front, where they merge into the 

 concave frontal limb; palpel)ral lobes small, elevated, separated from 

 the fixed cheeks b}' a shallow furrow, and situated opposite the cen- 

 tral part of the head; ocular ridges indicated by depressed lines that 

 extend from the anterior end of the palpebral lobes, across the fixed 

 cheeks, to the dorsal furrow; postero-lateral limb about one-third the 

 width of the head within the facial sutures; it is marked by a ))road, 

 shallow furrow within the narrow posterior margin; frontal limb 

 broad, concave, and rising with a gentle curvature from the front of 

 the glabella to the margin of the thickened frontal rim. 



Free check roughly subtriangular; it is divided into an interior, 

 convex bodA', which rises from the furrow at its base to the small eye 

 lobe at its center; the ))order of the head is crossed obli(|uoly l)y a 

 sharp ridge that extends from its inner, anterior side, backward 

 to its outer side, where it forms the outer edge of a sharp spine; the 

 border extends l)ackward to the postero-lateral angle of the cheek, and 

 inward to the facial suture; a strong spine originates a little in advance 

 of the postero-lateral angle and extends obliquely backward. 



The associated pygidium is subsemicircular; axial lobe strong, and 

 tapering gently from the front toward its rounded termination; it is 

 divided by five well defined, deep transverse furrows, that cross it 

 from side to side, and a sixth posterior furrow that crosses only its 



