DESCRIPTION OF GENERA AND SPECIES. 219 



This species differs from D. alccste [plate 22, fig. 3] in having a proportionately 

 longer frontal rim, less distinctly defined glabellar furrows, and in being less convex. 

 From other described species from the Chinese Cambrian it differs in having a 

 glabella that narrows toward the front instead of expanding. The associated 

 pygidium is much like that associated with D. deois [plate 22, fig. ih]. It differs 

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

 upon the pleural lobes. 



Formation and Locality. Middle Cambrian: (C'69) Limestone in shales about 

 65 feet (19.5 m.) above base of Ki-chou limestone [Willis and Blackwelder, 1907, 

 p. 145 (first list of fossils)], 4 miles (6.4 km.) east of Fang-lan-chon, Shan-si, China. 



Collected by Eliot Blackwelder. 



Genus HYSTEROLENUS Moberg. 



Hysterolenus MOBERG, 1898, Gtol. Furen. Stockholm Forhandl., vol. xx, p. 318. 



Hysterolenus ? spp. undt. 

 Plate 22, Figures 9, 90: Plate 23, Figure 9. 



Several pygidia occur in the collection that appear to be nearer the pygidia of 

 this genus than to any other described. One of them from Locality ('38 is illus- 

 trated by figure 9, plate 22 ; another from Locality ('56. by figure ga, and another 

 from Locality C64 by figure 9, plate 23. The latter reference is exceedingly doubtful, 

 as the side spine and surface are quite unlike the same features in the other specimens. 



All of the specimens are from the Upper Cambrian. Those represented by fig- 

 ures 9 and ga, plate 22, occur at the same horizon in the Ch'ang-hia limestone, and 

 that represented by figure 9, plate 23, from a higher horizon of the same limestone. 



Formation and Locality. Upper Cambrian: (C:'8) Crystalline limestone near 

 the base of the Ch'au-mi-tien limestone [Blackwelder, 1907^, p. 36 (part of first list 

 of fossils)], at Ch'au-mi-tien, Shan-tung, China. 



Collected by Eliot Blackwelder. 



From Locality C56, lower part of Ch'au-mi-tien limestone, 25 feet (7.5 m.) 

 below the top of Pagoda Hill [Blackwelder, 19071:, p. 42 (part of last list of fossils)], 

 i mile (1.6 km.) west of Tsi-nan, Shan-tung, China. 



Collected by Eliot Blackwelder and Li San. 



From Locality C<>4, upper limestone member of the Kiu-lung group [Black- 

 welder, 190717, pp. 37 and 42 (first list of fossils), and fig. 10 (bed 20), p. 38], 2.7 

 miles (4.3 km.) southwest of Yen-chuang, Sin-t'ai district, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Genus BATHYURISCUS Meek. 



Bathyuriscns MEEK, 1873. (See Walcott, 1886, Bull. V . S. Geol. Survey, No. 30. p. 215.) 



Bathyuriscus manchuriensis Walcott. 



Plate 23, Figures 2, 2a-f. 



Balhytiriscus manchuriensis WALCOTT, 1911, Smithsonian Misc. Coll., vol. 57, No. 4, pp. 97 99, plate 

 16, fig. 4. (Described and discussed as a new species essentially as below.) 



This species is founded on numerous specimens of the cranidium, free cheeks, 

 thoracic segments, and pygidium that are compressed in a fine argillaceous shale. 

 Unfortunately, there are no entire specimens of the dorsal shield. 



As restored by combining the free cheeks and cranidium, the cephalon is semi- 

 circular in outline and moderately convex. It is bordered by a narrow, slightly 

 rounded margin that is separated by a sharply defined narrow furrow from the 

 glabella and the slope of the free cheeks. The posterior border is very narrow, 



