DESCRIPTION OF GENERA AND SPECIES. 65 



Formation and Locality. Middle Cambrian : (C 62) Earthy layer in the middle 

 limestone of the Kiu-lung group [Blackvvelder, 19070, pp. 37 and 40 (last list of 

 fossils), and fig. 10 (base of bed 7), p. 38], 2.5 miles (4km.) south of Yen-chuang, on 

 the north-northeast spur of Hu-lu-shan, Sin-t'ai district, Shan-tung, China. 



Collected by Eliot Blackwclder. 



Also (35 n), Fu-chou series: Limestones near the base of the series just above 

 the white quartzite [see Blackwelder, 1907/7, p. 92, for general section giving strati- 

 graphic 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. 



Obolus damesi (Walcott). 



Plate 2, Figures i, \a-e. 

 Obolus (Lingulella) damesi WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxvm, p. 329. (Species described 



and discussed essentially as below.) 



Lingulella damesi ( WALCOTT), 1912, Monogr. U.S. Geol. Survey, vol. LI, p. 489, plate xxxix, figs. 8, Sa-c. 

 (A copy of the preceding reference. See footnote, p. 489.) 



The general description of Obolus chinensis [p. 64] applies so closely to this 

 species that it does not appear necessary to do more than call attention to the points 

 in which they differ. From 0. chinensis this species varies in having a more elon- 

 gate, acuminate ventral valve and ovate dorsal valve; the valves are also less 

 convex. The average size of the ventral valve is about 5 mm. in length by 3.5 mm. 

 in width. 



In Manchuria 0. damesi occurs abundantly in the limestones and shales of 

 the lower part of the Dorypyge richthofcni zone. 



The species is named after Dr. Wilhelm Dames, who first described the Cam- 

 brian faunas of China. 



Formation and Locality. Middle Cambrian: (CIO) Lower shale member of the 

 Kiu-lung group [Blackwelder, 1907(7, pp. 37 and 40 (part of the third list of fossils), 

 and fig. 8a (bed 35), p. 29], about 3 miles (4.8 km.) southwest of Yen-chuang; also 

 (C7), lower limestone member of the Kiu-lung group [Blackwelder, 19070, pp. 37 and 

 39 (last list of fossils), and fig. Sa (bed 33), p. 29], 2.2 miles (3.5 km.) southwest of 

 Yen-chuang ; and (C 64) , upper limestone member of the Kiu-lung group [Blackwelder, 

 19070, 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. 



Also (35 n, 35 r, and 36 c) Fu-chou series: Limestones near the base of the 

 series, just above the white quartzite [see Blackwelder, igojb, p. 92, for general 

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

 hsing-tau island; and (35o and 36 g) shales about 130 feet (40 m.) above the white 

 quartzite [see idem], collected in drainage cuts a short distance back from the bluff 

 (see 35n) forming the shore of Tschang-hsing-tau Island, also (36 h) collected in a low 

 bluff on the shore of Tschang-hsing-tau Island ; and (36(1) shales near the base of the 

 series just above the white quartzite [see idem], 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. 



Obolus matinalis (Hall)? 1 



Plate 2, Figures 2, 20. 



Lingidepis matinalis HALL, 1863, :6th Ann. Rept. N. Y. State Cab. Nat. Hist., p. 130, plate VI, figs, 

 12, 13. (Name proposed for the ovate form of shell associated with Lingidepis pinnaformis. 

 which is illustrated by figs. 12 and 13.) 



l The complete synonymy of this species will be found in vol. LI, Monographs U. S. Geol. Survey, 1912, pp. 

 400 and 402. 



