74 RESEARCH IN CHINA. 



Also at the following localities: (35 n and 35 r) Fu-chou series; limestones, and 

 (36 e) shales interbedded with limestones, near the base of the series just above the 

 white quartzite [see Blackwelder, 19076, p. 92, for general section giving strati- 

 graphic relations]; collected in a low bluff on the shore of Tsching-hsing-tau Island; 

 and (35o and 36 g) 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 35 n] 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. xxvm, p. 303. (Described as below 



as a new species.) 

 Acrothele ? minuta WALCOTT, 1912, Monogr. U. S. Geol. Survey, vol. Li, p. 650, plate LXIII, 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 striae. 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: (CG) Thin, platy limestone in 

 the upper shale member of the Kiu-lung group [Blackwelder, 19070, 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, 8<i. 



Acrothele rarus WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxvm, p. 303. (Described and discussed 



as below as a new species.) 

 Acrothele rara WALCOTT, 1912, Monogr. U. S. Geol. Survey, vol. LI, pp. 656-656, plate LXIII, figs. 4 



and 40. (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 Acroihelc sitbsidua (White) Walcott 

 [19126, plate LX, figs, i, ia-o}. 



