96 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



medium length marked b^^ a strong furrow parallel to the posterior 

 margin; frontal limb narrow, slightly concave, and almost concealed 

 by the overhanging, almost tumid frontal portion of the glabella. 



Surface smooth under a strong lens. The largest of the three heads 

 representing this species has a length of T mm. exclusive of the 

 occipital spine. 



Formation and locality. — Middle Cambrian. Lower portion of 

 Chang' Hsia formation in a drab-colored limestone, intercalated in 

 green nodular shale. At Yen Chuang and 2 miles south, lisin Tai, 

 Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



DOLICHOMETOPUS DIRCE, new species. 



Only the central portions of the head of this species are known. 

 It differs from I), deols in the nearly parallel sides of the glabella, the 

 absence of glabellar furrows, and ver}^ short, almost flat frontal limb. 

 The occipital lobe is nearly one-half the length of the head. 



Surface under strong magnifier smooth. The tj^pe specimen of the 

 head has a length of 11 mm. 



Formation and locality. — Middle Cambrian. Near the upper por- 

 tion of the Chang Hsia formation. Two miles east of Chang Hsia, 

 Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



Genus ILL^^NURUS Hall. 

 ILLiENURUS CANENS, new species. 



Head, exclusive of the free checks, sub-rhomboidal in outline, mod- 

 erately ' convex. Glabella sub-quadrate, moderately convex, length 

 and width the same, without perceptible occipital or dorsal furrows; 

 palpe1)ral lobes small, with their anterior end opposite the center of 

 the glabella; frontal margin broadly rounded; postero- lateral limbs 

 short and subtriangular in outline; the facial suture, cutting the frontal 

 rim on a line with the base of the palpebral lobe, passes directly to the 

 anterior margin of the palpebral lobe; it encircles the latter, and then, 

 curving gently outward, passes in an almost direct line to the posterior 

 lateral margin of the ]30stero-lateral limb. 



Surface minutel}" punctate under a strong lens. 



The p3^gidia associated with the head parts are rounded, subtriangular 

 in outline, and about two-thirds as long as the width at the anterior 

 margin, rather convex, and marked on the interior of the cast b}^ a 

 faintly defined, rather narrow axis, and very slight traces of ten or 

 more transverse furrows on the axis, that are more faintly indicated 

 for a short distance on the pleural lobes. 



