12 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



Dorsal valve with a minute apex from which a narrow, slightly 

 developed median fold extends out to about the center of the shell, 

 where it becomes elevated and projects forward to the front margin; 

 the remaining- portions of the surface are uniformly convex, sloping 

 away from the median fold to the margins of the valve. 



Nothing is known of the interior of either valve. 



Ohservcdions. — In general form this species resembles SyntropJda 

 priiiiordiaUs of the St. Croix sandstone of Wisconsin." It diflers in 

 its more rounded irregularly oval form and the ver}^ large median 

 sinus of the ventral valve. 



Forinatioii and locality. — Upper Cambrian. Central portion of Chao 

 Mi Tien limestone, Pagoda Hill, 1 mile southwest of Tai An Fu, and at 

 a somewhat 4ower horizon two-thirds of a mile west of Tai An Fu, 

 Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



GASTROPODA. 



Genus SCENELLA Billings. 

 SCENELLA CLOTHO, new species. 



Shell small, moderately convex; apex' elongate, slightly eccentric, 

 elevated; aperture irregularly oval; a narrow carina extends from the 

 apex down to the broader end, and several obscure carinte radiate from 

 the apex toward the margin. 



Surface marked by line concentric strii\3 and very tine radiating 

 striaj. 



The type specimen has a length of 4.25 mm.; greatest width 3 mm.; 

 elevation of apex about 1.5 mm. 



This species is clearly distinguished b}' the broad, elliptical, or sub- 

 ovate form of its aperture and elongated apex; the latter feature is 

 determined from the interior of the shell, which indicates that the 

 apex was situated somewhat nearer the narrower end of the aperture; 

 this feature suggests that if there were perfect specimens representing 

 the species, it might be found to be more nearly related to some forms 

 of Stenotheca than to Scenella. 



Formation and locality. — Middle Cambrian, upper portion of Chang 

 Hsia formation, 1 mile east of Chang Hsia, Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



SCENELLA, species undetermined. 



This species is represented b}' a cast of the interior of a small, 

 patelloid shell, with an oval aperture measuring 2 ))y 3 mm. and 



«Proc. U. S. Nat. Mus., XXVIll, 1905, p. 292. 



