DESCRIPTION OF GENERA AND SPECIES. 69 



Formation and Locality. Middle Cambrian : Ch'ang hia limestone (C 1 and 

 C2), lower shale member of the Kiu-lung group [Blackwelder, 19070, pp. 37 and 

 40 (part of the third list of fossils), and fig. 10 (beds 4 and 5), p. 38], 2 miles (3.2 km.) 

 south of Yen-chuang, and (C6) thin, platy limestone in the upper shale member 

 of the Kiu-lung group [idem, pp. 37 and 41 (second list of fossils), and fig. 10 (bed 12), 

 p. 38], 2.5 miles (4 km.) southwest of Yen-chuang, Sin-t'ai district, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Obolus (Westonia) sp. undt. Walcott. 



Ololus (Westonia) sp. undt. a WALCOTT, 1912, Monogr. U. S. Geol. Survey, vol. LI, p. 468. (Discussed.) 



Fragments of shell marked with stronger transverse, irregular, sharp ridges 

 occur a little higher in the Cambrian section of Shan-tung that clearly indicate 

 a species of \Vestonia distinct from Obolus (Westonia) blackwelderi Walcott. 



Formation and Locality. Upper Cambrian: (C56) Lower part of Ch'au-mi- 

 tien limestone, 25 feet (7.5 m.) below the top of Pagoda Hill [Blackwelder, 19070, p. 

 42 (part of last list of fossils)], i mile (1.6 km.) west on Tsi-nan, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Genus LINGULELLA Salter. 



For discussion of this genus see Monogr. U. S. Geol. Survey, vol. LI, 1912, 

 pp. 468-474- 



Lingulella manchuriensis Walcott. 



Plate 3, Figures i, la-e. 



Lingulella manchuriensis WALCOTT, 1911, Smithsonian Misc. Coll., vol. 57, No. 4, p. 74, plate 14, figs. 



2 and 20. (Described and discussed as a new species essentially as below.) 



This species and Lingulella mar da belong to a group of small, elongate, oval 

 shells that are represented in the Rocky Mountain Province Cambrian fauna by 

 Lingulella inanticnla (White) [Walcott, 19126, plate xx, figs, i, lac], and the Atlantic 

 Province fauna by L. atava (Matthew) [Walcott, 19126, plate xxxv, figs. 5, ^a-h], 

 L. collicia (Matthew) [Walcott, 19126, plate xxxv, figs, i, la-e], L. ferruginea Salter 

 [Walcott, 19126, plate xxix, figs, i, la-w, 2, 2 a-/, and plate xxxv, figs. 4, 40-6], 

 L. nanno (Walcott) [19126, plate xxiv, figs, i, la-d], and a number of similar forms 

 illustrated on plates xxi and xxxv of Monograph LI, U. S. Geological Survey. 

 L. manchuriensis appears to be most nearly related to L. siniilis (Walcott) [19126, 

 plate xxi, figs. 2, 2 a-/, 3, ^a-d]. It differs in the broader, more rounded posterior 

 half of the ventral valve. 



The average length of the ventral valve is 3 mm. among the large number of 

 shells that occur in both limestone and shale. 



Formation and Locality. Middle Cambrian : (35 p) Fu-chou series; shales about 

 80 feet (24 m.) above the white quartzite [see Blackwelder, 19076, p. 92, for general 

 section giving stratigraphic relations] ; collected in a low bluff on the shore of Tschang- 

 hsing-tau Island, east of Niang-niang-kung, Liau-tung, Manchuria, China. 



Collected by J. P. Iddings and Li San. 



Lingulella marcia Walcott. 



Plate 2, Figures 6, 6a-f. 



Lingulella marcia WALCOTT, 1911. Smithsonian Misc. Coll., vol. 57, No. 4, pp. 74-75, plate 14, figs. 



3 and 30. (Described and discussed as a new species essentially as below.) 



This species is one of the small forms allied to the group of similar shells 

 mentioned under L. manchuriensis. It differs from the latter species in being 



