50 BULLETIN 164, UNITED STATES NATIONAL MUSEUM 



Genus YANGTZEELLA Kolarova, 1925 



YANGTZEELLA RETICULATA, new epecies 



Plate 36, Fiqueb 9 



One good pedicle valve and a cast of another occur in Louder- 

 back's collection from central China, 



Description. — Shell medium, semicircular; hinge line perhaps 

 straight, about equaling the diameter of the shell. Pedicle valve 

 convex, smaller, rather prominent along the median line, mesial fold 

 being about one-half of the total width of the shell and scarcely 

 differentiated from the lateral slopes; beak comparatively small, 

 slightly incurved. The spondylium is supported by a median and 

 two lateral septae. 



External surface of valve ornamented by verj'^ fine radiating and 

 concentric striae, which make a very fine netlike reticulation. 



The dimensions of a pedicle valve are: Length, 22 mm; width, 

 27 mm, 



Comparisons. — This species may be compared with Yangtzeella 

 poloi (Martelli) from central China, but it is distinguished from 

 it by the rounded and more convex shell and the fine surface 

 ornamentation. 



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

 China, 



Holotype.—V.^.'^M. No, 83646. 



GASTROPODA 

 Genus PHRAGMOLITES Conrad, 1838 



PHRAGMOLITES, species undetermined 



Plate 23, Figube 10 



A single small specimen of gastropod (U.S,N,M, No, 8347) was 

 collected from the Wuting formation. Even though this specimen is 

 small, it shows characteristic features of the genus Phragmolites 

 and appears to belong to a new species. Though it is too fragmen- 

 tary to deserve a specific name, I shall describe it as far as possible. 



Description. — Shell small, 5.5 mm in diameter, laterally com- 

 pressed, consisting of two and a half volutions; whorls slightly 

 wider than the height, somewhat depressed, rounded in sections, 

 gently convex on the sides. Surface very rough and strongly un- 

 dulated, about nine lamellae crossing the last whorl almost directly, 

 about 1 mm apart. Between lamellae the whorls are marked by very 

 fine lines of growth, which run parallel to the lamellae. 



