102 RESEARCH IN CHINA. 



and flat border on the pygidium. It is of the type of and very closely related to 

 A. paroifrons Linnarsson [1869; see Tullberg, 1880, plate 2, figs. 27, 28], from which 

 it differs in the proportion of the glabella to the length of the cephalic shield and 

 in the flatter margins of the cephalic and caudal shields. 



Formation and Locality. Middle Cambrian: (C57) In limestone nodules in 

 the lower shale member of the Kiu-lung group [Blackwelder, 19070, pp. 37 and 40 

 (first list of fossils)], 3 miles (4.8 km.) south of Kao-kia-p'u, and 4 miles (6.4 km.) 

 north of Sin-t'ai-hien, Sin-t'ai district, Shan-tung, China. 



Agnostus parvifrons latelimbatus Lorenz. 

 Plate 7, Figures i, ia. 



Agnostus parvifrons latelimbatus LORENZ, 1906, Zeitschr. deutsch. geol. Gesellsch., vol. LVIII, pt. II, 

 p. 84, plate 4, figs. 9, 90-6; plate 5, figs. 10, 11. (Described and illustrated as a new variety.) 



The original specimens of this variety of Agnostus parvifrons Linnarsson are 

 unsatisfactory. The species is represented, but the characters for determining the 

 variety are not clear, owing to the imperfect specimens. 



Formation and Locality. Middle Cambrian: Kiu-lung group, Wang-tschuang, 

 Shan-tung, China. 



Agnostus sp. undt. 



One specimen of a pygidium of an Agnostus of the same general character as 

 that of A. doumllei Bergeron [p. io&] occurs in limestones of the lower Ch'au-mi-tien 

 formation. In the absence of the cephalon I will only call attention to the occur- 

 rence. 



Formation and Locality. Upper Cambrian: (CS4) Purplish-gray limestone 

 about 100 feet (30 m.) above the base of the Ch'au-mi-tien formation [Blackwelder, 

 19070, p. 36 (part of first list of fossils)], in road at northeastern corner of small 

 village near Ch'au-mi-tien, Shan-tung, China. 



Collected by Eliot Blackwelder. 



A species of Agnostus is indicated in the upper beds of the Ch'ang-hia formation 

 by the presence of a single pygidium that differs from A. chincnsis Dames [p. 99] 

 in having a proportionately stronger and more rounded marginal rim. The median 

 lobe is not so broad in its posterior half and not so convex. 



Formation and Locality. Middle Cambrian : (C 24) Near top of black oolite group 

 in the uppermost layers of the Ch'ang-hia formation [Blackwelder, 19070, p. 33 

 (part of last list of fossils)], 2 miles (3.2 km.) east of Ch'ang-hia, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Genus MICRODISCUS Emmons. 

 Microdiscus Emmons, WALCOTT, 1886, Bull. U. S. Geol. Survey, No. 30, p. 152. 



Microdiscus orientalis Walcott. 

 Plate 7, Figure 10. 



Microdiscus orientalis WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 24. (Described and dis- 

 cussed as a new species essentially as below.) 



There is in the collection but a single specimen of the matrix of a portion of 

 the cephalon of this species. This indicates the cephalon to have been semicircular 

 in outline, with a strong, rounded, frontal border, marked by ten or more transverse 

 furrows, very much in the same manner as M. connexus Walcott [1887, p. 194, plate i, 

 figs. 4, 46]. In front of the border there is a very narrow, slightly elevated rim. 



