DESCRIPTION OF GENERA AND SPECIES. 85 



19070, p. 33 (part of the last list of fossils)], 2 miles (3.2 km.) north-northeast of 

 Ch'ang-hia, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Eoorthis sp. undt. (6) (Walcott). 1 

 Plate 4, Figure 9. 



Eoorthis sp. undt. d (WALCOTT), 1912, Monogr. U.S. Geol. Survey, vol. Li, p. 793, plate LXXXIX, fig. 8. 

 (Described and discussed as below.) 



A larger shell of this type [see plate iv, fig. 9] occurs in Shan-si, in the central 

 portion of the Ki-chou formation. It has a length of 6.5 mm. and a width of 

 7.5 mm. The surface is marked by numerous radiating ribs, similar to those of 

 the shell from Ch'ang-hia, also concentric stride and several ridges resulting from 

 interruption of growth. 



Formation and Locality. Middle Cambrian: (C71) Massive cliff-making lime- 

 stone in the central portion of the Ki-chou formation [Willis and Blackwelder, 1907, 

 pp. 139 and 145 (second list of fossils)], 4 miles (6.4 km.) southwest of Tung-yii, 

 vShan-si, China. 



Collected by Bailey Willis and Eliot Blackwelder. 



Genus HUENELLA Walcott. 



For discussion of the genus Hnciiclla see Monogr. U. S. Geol. Survey, vol. LI, 

 1912, p. 805. 



Huenella orientalis (Walcott). 



Plate 4, Figures 14, i^a-b. 



Synlrophia. orientalis WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxviu, p. 292. (Characterized and 



discussed as below as a new species.) 

 Huenella orientalis (WALCOTT), 1912, Monogr. U. S. Geol. Survey, p. 808, plate civ, figs. 3,30-6. (Copy 



of the preceding reference.) 



This species is closely related in form and surface characters to Huenella texana 

 (Walcott) [19126, p. 808, plate cm, figs, i, ia-i] and some forms of H. abnormis 

 (Walcott) [idem, pp. 805-806, text fig. 13, p. 299, and plate cm, figs. 2, aa-ra]. It 

 differs from them in details of surface ribs. On the dorsal valve there are two or three 

 faintly defined, radiating ribs on each side of the median fold, which has obscure 

 ribs upon it. Corresponding ribs occur upon the mesial depression of the ventral 

 valve and the side slopes adjoining the depression. The material representing it 

 is too limited to warrant an identification with any described species. Huenella 

 orientalis is the trans-Pacific representative of H. texana (Walcott). 



Formation and Locality. Upper Cambrian: (06-1) 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. 



Genus SYNTROPHIA Hall and Clarke. 



For discussion of the genus Syntrophia see Monogr. U. S. Geol. Survey, vol. w, 

 1912, pp. 798-799- 



Syntrophia orthia Walcott. 



Plate .s, Figures i, ta-b. 



Syntropliia orthia. WALCOTT, 1905. Proc. U. S. Nat. Mus., vol. xxix, pp. 11-12. (Described and dis- 

 cussed as a new species essentially as on page 86.) 



Syntrophia orthia WALCOTT, 1912, Monogr. U. S. Geol. Survey, vol. Li, p. 803, plate civ, figs. 4, 40-6. 

 (Copy of the preceding reference.) 



'See synonymy for Eiwrthis sp. undt. (a), p. 84. 



