DESCRIPTION OP GENERA AND SPECIES. 131 



three pairs of short, well-defined furrows that divide the sides of the glabella into 

 four subequal lobes; an occipital spine and a narrow, rounded frontal rim, cut 

 around in front nearly to the median line by the facial sutures. Palpebral ridge 

 well defined. Surface unknown. 



Formation and Locality. Lower Cambrian: (C20) Central part of the Man-t'o 

 shale formation [Blackwelder, 19070, p. 26 (last list of fossils), and fig. 6 (bed 14), 

 p. 25], on the west side of an isolated butte i mile (1.6 km.) south of Ch'ang-hia; 

 also (C17), ferruginous limestone nodules in the brown sandy shales at the top of 

 the Man-t'o shale [idem, p. 27 (list of fossils at top of page), and fig. 6 (bed 15), p. 25], 

 and (C31) gray crystalline limestone in the central portion of the Man-t'o shales 

 [idem, p. 26 (first list of fossils), and fig. 6 (bed 12), p. 25], both at Ch'ang-hia, 

 Shan-tung, China. 



Collected by Eliot Blackwelder. 



Ptychoparia granosa Walcott. 



Plate 12, Figure 7. 



Ptychoparia granulosa WAI.COTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 78. (Species described as 

 below. This species is believed to be congeneric with Hall and Whitefield's species; since the 

 name granulosa is therefore preoccupied for Ptychoparia, granosa is proposed.) 



Not Crepicephalus (Loganclius) grarnilosus HALL and WHITEFIELD, 1877, Gcol. Expl. Fortieth Parallel, 

 vol. iv, p. 214, plate 2, figs. 2 and 3. 



Plychoparia granosa WALCOTT, 191 1, Smithsonian Misc. Coll., vol. 57, No. 4, pp. 77-78, plate 14, fig. 8. 

 (Species described and discussed essentially as below.) 



The gently convex central portions of the cephalon, exclusive of the free 

 cheeks, are all that is known of this species. These indicate a rather broad, semi- 

 circular cephalon, with small free cheeks, wide fixed cheeks, narrow, short, convex 

 glabella, and narrow, flattened frontal rim ; glabella marked by three pairs of faintly 

 impressed but clear glabellar furrows; frontal space between the glabella and rim 

 broader than the frontal rim and slightly convex ; palpebral ridge narrow, clearly 

 defined, and merging into a rather small eye-lobe. 



vSurface slightly granulose. 



Formation and Locality. Lower Cambrian : (C 17) Ferruginous limestone nodules 

 in the brown sandy shales at the top of the Man-t'o shale [Blackwelder, 19070, p. 27 

 (list of fossils at top of page), and fig. 6 (bed 15), p. 25], at Ch'ang-hia, Shan-tung, 

 China, 



Collected by Eliot Blackwelder. 



Ptychoparia impar Walcott. 

 Plate 12, Figures 9, ga. 



Plychoparia impar WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 78. (Characterized as a new 

 species.) 



This species is represented by many fine specimens of the rather convex central 

 portions of the head. The form of the parts preserved is not unlike that of Ptycho- 

 paria aclis [p. 130]. They differ in being stronger and more convex, in the absence 

 of an occipital spine, and the presence of rather faint glabellar furrows. Palpebral 

 ridge rounded and rather strong. 



Surface finely punctate. 



Formation and locality. Lower Cambrian: (C17) Ferruginous limestone nod- 

 ules in the brown sandy shales at the top of the Man-t'o shale jBlackwelder, 19070, 

 p. 27 (list of fossils at top of page), and fig. 6 (bed 15), p. 25], at Ch'ang-hia, Shan- 

 tung, China. 



Collected by Eliot Blackwelder. 



