DESCRIPTION OF GENERA AND SPECIES. 283 
Plectorthis willisi Weller (plate 25, figs. 10, 11). 
1907. Plectorthis willisit Weller, Proc. U. S. Nat. Mus., vol. XXXII, p. 557. 
Shell transversely subelliptical in outline, the hinge-line a little shorter than 
the greatest width, cardinal extremities slightly rounded. Pedicle valve depressed- 
convex, slightly compressed toward the cardinal extremities; the beak small, scarcely 
incurved, cardinal area a little concave, sloping backward at an angle of about 40° to 
the plane of the valve; cardinal margins angular. Brachial valve nearly as convex 
as the pedicle, compressed toward the cardinal extremities. Surface of each valve 
marked by from 20 to 25 major radiating, rounded coste, which increase in width 
conspicuously in passing from the beak to the front margin; in each interspace 
between these major coste from one to three smaller ones which do not reach the 
beak are intercalated. The more minute surface markings are destroyed. The 
dimensions of a pedicle valve are: length 7.5 mm., width 12 mm., height of area 1 
mm., convexity 2 mm. 
The most notable feature of this shell is the conspicuous broadening of the 
major cost in passing from the beak to the front margin. 
Dalmanella testudinaria (Dalman) (plate 25, figs. 12-16). 
1828. Orthis testudinaria Dalman, Kongl. Svenska Vet.-Skad. Handl. for 1827, p. 115, plate 2, fig. 4. 
1847. Orthis testudinaria Hall, Pal. N. Y., vol. 1, p. 117, plate 32, fig. 1; p. 288, plate 79, fig. 4. 
1863. Orthis testudinaria Billings, Geol. Canada, p. 165, fig. 144. 
1869. Orthis testudinaria Davidson, Brit. Sil. Brach., vol. 11, p. 226, plate 28, figs. 13-24. 
1882. Orthis testudinaria Whitfield, Geol. Wis., vol. Iv, p. 258, plate 12, figs. 5-7. 
1884. Orthis testudinaria Walcott, Monog. U.S.G.S§., vol. vim, p. 72, plate 11, fig. 10. 
1892. Dalmanella testudinaria Hall and Clarke, Pal. N.Y., vol. vi, pt. 1, pp. 190, 206, 218, 224, plate 
5B, figs. 27-39. 
1893. Orthis (Dalmanella) testudinaria Winchell and Schuchert, Minn. Geol. Survey, vol. 11, pt. 111, pp. 
ETT A2AT. 
1897. Orthts testudinaria Sardeson, Am. Geol., vol. XIx, p. 92. 
1903. Dalmanella testudinaria Weller, Pal. N. J., vol. 111, p. 155, plate 10, figs. 1, 2. 
This species is one of the most widely distributed brachiopods found in strata of 
Ordovician age, it being recognized throughout the world wherever middle Ordo- 
vician strata are known. In the fauna of the Ki-sin-ling limestone it is the most 
abundant species. The specimens agree well with representatives of the same spe- 
cies from North America, but are, on the average, perhaps, slightly more elongate. 
The average size of the specimens in the collection is about 13 mm. in length and 14 
mm. in width. 
Dalmanella subeequata (Conrad) (plate 25, figs. 19, 20). 
1843. Orthis subequata Conrad, Proc. Acad. Nat. Sci. Phila., vol. 1, p. 333. 
1847. Orthis subequata Hall, Pal. N. Y., vol. 1, p. 118, plate 32, fig. 2. 
1862. Orthis subequata Hall, Geol. Wis., vol. 1, p. 42, figs. 1-3, and p. 436. 
1892. Dalmanella subequata Hall and Clarke, Pal. N. Y., vol. vim, pt. 1, pp. 194, 207, 224, plate 5¢, figs. 
6-11. 
1893. Orthis (Dalmanella) subequata Winchell and Schuchert, Minn. Geol. Surv., vol. 11, p. 446, plate 
33, figs. 30-36. 
1903. Dalmanella subequata Weller, Pal. N. J., vol. 11, p. 156, plate 10, figs. 3-4. 
In North America this species is a variable one, no less than four named varieties 
being recognized by Schuchert in his “Synopsis of American Fossil Brachiopoda.”’ 
The Chinese specimens are entirely similar to American ones and agree for the most 
part with the typical form of the species, though some of those with slightly coarser 
costz might perhaps be referred to the variety pervetus. The gibbosus variety with 
well-developed sinus has not been detected in the Chinese collection. 
Clitambonites chinensis Weller (plate 25, figs. 17, 18). 
1907. Clitambonites chinensis Weller, Proc. U. S. Nat. Mus., vol. xxxu, p. 558. 
Shell broader than long, the hinge-line straight, the greatest width at the hinge- 
line or a little in front of it, the lateral and anterior margins describing a regular 
