FORMATION'S AND FOSSILS OF SOUTH MANCHURIA 45 



Formation and locality. — ^Lower Ordovician, Wuting formation: 

 In gray banded limestone near Ta-pu, just north of the Pen-hsi-hu 

 colliery, Liao-tung, Manchuria. 



Genus RAFINESQUINA Hall and Clarke, 1892 



RAFINESQUINA PUTEATA, new species 



Plate 34, Figures 22-24 



Description. — This species is represented by two pedicle valves, 

 both more or less incomplete. Shell semielliptical, gently convex; 

 hinge line equal to width of shell; cardinal angle rectangular or 

 slightly obtuse ; hinge line not denticulate ; beak small, scarcely rising 

 above hinge line. Surface of valve covered with numerous subequi- 

 distant regular, straight, threadlike, primary radii of equal strength, 

 some continuous from beak to margin, others originating at half or 

 less than half their length ; interspaces with 2 to 4 very fine, thread- 

 like lines ; whole surface of shell crossed by very delicate concentric 

 lines. Substance of shell finely and densely pitted. 



Comparisons. — The general outline of this species resembles 

 Rajlnesqmna alternata (Emmons), an American species from the 

 Trenton-Richmond groups, but the pitted surface and the finer radi- 

 ating lines between the primary riblets serve to distinguish it readily. 

 Also the English variety Raflnesquina expansa marcallMrai Reed, 

 from the Stinchar limestone group, bears a close resemblance but 

 differs from the new species in having punctated instead of the pitted 

 surface. 



Formation and locality. — Ordovician : Near Huang-pa-yi, Shensi, 

 China. 



(7o%^es.— U.S.N.M. No. 83637. 



RAFINESQUINA species undetermined 



Plate 23, Figures S, 9 



Several poorly preserved specimens of Raflnesquina (U. S. N. M. 

 Nos. 83638 and 83639), in size, outline, convexity, degree of genicula- 

 tion anteriorly, and manner of striation appear to be closely allied 

 to R. alternata (Emmons), from the Ordovician strata of North 

 America. . One of the most complete specimens from the Hsiao- 

 shih district is a pedicle valve, 21.5 mm long and 25 mm wide with 

 a convexity of 4 mm. The surface of the shell is marked by numer- 

 ous radiating striae, alternating in size, with from one to four finer 

 striae lying between the coarser ones. These radiating striae are 

 crossed by finer concentric lines. 



The outlines of the specimen from Hsiao-shih (pi. 23, fig. 9) and 

 the one from Wu-hu-tsui (pi. 23, fig. 8) differ somewhat, and it is 

 possible that they may represent different species or varieties. 

 101621—32 4 



