CAMBBJAN FAUNAS OF CHINA-WALCOTT. 595 



ridge extends obliqueh^ across the narrow fixed cheek; frontal rim 

 short and nearl}^ flat; the curved angle at the union of the fixed cheeks 

 and glabella gives the impression that the frontal rim is slightly 

 concave. 



Associated free cheek subtriangiilar, with a long genal spine. 



Surface, as seen b_y a .strong lens, slightl}- roughened with minute 

 granules. The type and only specimen in the collection has a length 

 of 7.5 mm. 



The associated pygidium is transverse, semicircular, and convex; 

 axial lobe convex, a little more than three-fourths the length of the 

 P}'gidium, and crossed by three rather clearly defined, narrow furi'ows, 

 that difl'erentiate three rings and a terminal portion; the outline of 

 the axis is continued by a low swelling that extends from the end of 

 the convex axis to the posterior margin; the furrows crossing the axis 

 curve outward and slightly backward across the pleural lobes to the 

 margin of the border; the}- are l)roader than the furrows on the axis 

 and separate three rather clearly defined segments from a narrow 

 frontal rim and a posterioi- poition back of the axis; border rela- 

 tively narrow, and sloping gentl}' from the base of the pleural lobe to 

 the outer margin; it arches slightly inward back of the axis. The 

 largest specimen has a width of 2() mm., with a length of 14 mm. A 

 small specimen 15 mm. in width has a less clearh' defined border, and 

 in other respects resembles the pygidium associated with D. deois 

 Walcott." 



Observations. — This species differs from D. alceste Walcott-' in 

 having a proportionately longer frontal rim, less distinctly defined 

 glabellar furrows, and in being less convex. From other described 

 species of the Chinese Cambrian it difl'ers in having a glabella that 

 narrows toward the front instead of expanding. The associated 

 pygidium is much like that associated with D. deois Walcott.^ It 

 difters in having a narrower, more clearly defined border, and more 

 clearly defined furrows upon the pleural lobes. 



Formation and locality .-~M.\did\Q Cambrian, lower portion of oolitic 

 limestone series; 4 miles east of Fang-lan-chon, Shan-si, China. 



Collected by Eliot Blackwelder. 



«Proc. U. S. Nat. Mu8., XXIX, 1905, p. 94. 



