74 RESEARCH IN CHINA. 
Also at the following localities: (85n and 35r) Fu-chéu series; limestones, and 
(36e) shales interbedded with limestones, near the base of the series just above the 
white quartzite [see Blackwelder, 1907), p. 92, for general section giving strati- 
graphic relations]; collected in a low bluff on the shore of Tschang-hsing-tau Island; 
and (350 and 36g) shales, about 130 feet (40 m.) above the white quartzite [see 
Blackwelder, idem], collected in drainage cuts a short distance back from the bluff 
[see 35n] forming the shore of Tschang-hsing-tau Island; all east of Niang-niang- 
kung, Liau-tung, Manchuria, China. 
Collected by J. P. Iddings and Li San. 
Acrothele ? minuta Walcott. 
Plate 3, Figure 7. 
Acrothele ? minuta WALCOTT, 1905, Proc. U.S. Nat. Mus., vol. xxvitt, p. 303. (Described as below 
as a new species.) 
Acrothele ? minuta WaLcoTT, 1912, Monogr. U.S. Geol. Survey, vol. LI, p. 650, plate LxmI, fig.3. (A 
copy of the preceding reference.) 
Shell minute, 1.5 mm. in diameter, subcircular in outline, gently convex, with 
a slight median depression from the umbo to the anterior margin; back of the umbo 
there is a sharp median depression between minute ridges, on each of which there 
are two points of nipples. Surface marked by fine, concentric strie. Substance 
of shell apparently phosphatic. 
This interesting little species is represented by a single specimen. The generic 
reference is somewhat doubtful. 
Formation and Locality—Middle Cambrian: (C6) Thin, platy limestone in 
the upper shale member of the Kiu-lung group [Blackwelder, 1907a, 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. 
Acrothele rara Walcott. 
Plate 3, Figures 8, 8a. 
Acrothele rarus WALCOTT, 1905, Proc. U.S. Nat. Mus., vol. xxv, p. 303. (Described and discussed 
as below as a new species.) 
Acrothele rara WaLcorTt, 1912, Monogr. U. S. Geol. Survey, vol. L1, pp. 656-656, plate Lx1m, figs. 4 
and 4a. (A copy of the preceding reference.) 
Of this shell only the interiors of the valves are known. Shells of average size 
are about 3.5 mm. in diameter. The outline of the valve is subcircular, the trans- 
verse diameter being slightly more than the length of the valve; the interior of the 
ventral valve shows that the valve was moderately convex, with a perforated apex 
about 0.5 mm. from the posterior margin; a short, broad median ridge extends for 
a short distance in front of the foraminal opening and short, narrow ridges extend 
obliquely forward from each side of the opening ; what may be the lateral muscle-scars 
occur close to the postero-lateral margins. In the dorsal valve a strong median ridge 
extends from the posterior margin to the center of the valve; this ridge is angular at 
the summit and broadest toward its anterior end; a vascular sinus starts on each 
side of the base of the median ridge and extends obliquely forward. 
The dark interior surface of the valves is marked by concentric lines that give 
a somewhat laminated appearance to the surface. From the manner in which 
the shell adheres to the limestone matrix it is probable that its outer surface is 
roughened by raised lines, somewhat as on Acrothele subsidua (White) Walcott 
[1912b, plate Lx, figs. 1, 1a-o]. 
