226 RESEARCH IN CHINA. 
latter is in about the same position as the tubercle on A. bergeroni [p. 225] but A. 
bergeroni is quite different in its outline and convexity. 
Formation and Locality —Middle Cambrian: (C32) A fine-grained bluish-black 
limestone bowlder believed to have come from the lower part of the Ki-sin-ling 
limestone [Blackwelder, 1907c, p. 272]; collected in river drift 1 mile (1.6 km.) south 
of Chén-p’ing-hién, on the Nan-kiang River, southern Shen-si, China. 
Collected by Bailey Willis and Eliot Blackwelder. 
Aluta eris (Walcott). 
Plate 23, Figure 12. 
Bradoria eris WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxrx, p. 100. (Species described as below.) 
General outline obliquely semicircular. Hinge-line straight; anterior cardinal 
angle about 70°; posterior cardinal angle slightly obtuse; anterior margin nearly 
straight to where it merges into the rounded lower margin; posterior margin gently 
rounded from the angle down to where it merges into the lower margin. Surface 
moderately convex, with the highest point at the tubercle a little in front of the 
center; a very narrow rim extends from the posterior cardinal angle around to the 
anterior side, where it broadens out and continues to the anterior cardinal angle; 
a slight, narrow ridge extends obliquely inward a short distance from the anterior 
cardinal angle to a furrow that extends from the hinge-line at right angles a short 
distance; the ridge and furrow outline a small lobe; from the inner angle, formed 
by the furrow and ridge described, a very narrow ridge extends downward, sub- 
parallel to the anterior margin, to the base of a strong, elevated tubercle or spine 
that is situated on the anterior third a little in advance of the transverse center of 
the valve. 
Under a strong lens the surface appears to be slightly roughened by shallow 
puncte. 
Width, 2 mm.; length, 1.5 mm.; depth, about 0.5 mm. 
This species differs from Aluta sterope [p. 227] in the outline of its valve and the 
presence of an elevated tubercle near the center. 
Formation and Locality —Middle Cambrian: (C32) A fine-grained bluish-black 
limestone bowlder believed to have come from the lower part of the Ki-sin-ling 
limestone [Blackwelder, 1907c, p. 272]; collected in river drift 1 mile (1.6 km.) south 
of Chén-p’ing-hién, on the Nan-kiang River, southern Shen-si, China. 
Collected by Bailey Willis and Eliot Blackwelder. 
Aluta fragilis (Walcott). 
Plate 23, Figure 13. 
Bradoria fragilis WaLcorr, 1905, Proc. U. S. Nat. Mus., vol. xxrx, p. 100. (Species described as 
below.) 
Hinge-line nearly straight, about one-fifth shorter than the width of the valve; 
posterior cardinal angle obtuse, with the marginal curve long and passing into the 
broad curve of the lower end of the valve; anterior cardinal angle about 75°, with 
the anterior margin nearly straight to where it merges into the broad curve of the 
lower part of the valve. Surface of the valve wrinkled to such an extent that it 
looks like wrinkled parchment. What may be an ocular tubercle occurs a short 
distance from the hinge and anterior margin. 
Surface minutely punctate under a strong lens. 
Width, 2.25 mm.; length, 2 mm.; depth, unknown, as the flexible test has been 
compressed. 
