N0.1395. CAMBRIAN BRACHIOPODA—WALCOTT. 327 



OBOLUS SHENSIENSIS, new species. 



General form ovate, with the ventral valve Ijroadh' subacuniiiiate 

 and dorsal valve obtusely rounded. Valves moderately convex in the 

 specimens embedded in a fine-grained, dark limestone. Surface marked 

 l)y fine, sharp, concentric strias and traces of irregular, obscurely 

 defined, low, radiating ridges; the interior layers show tine radiating 

 strife and concentric lines. The shell is strong and built up of numer- 

 ous lamelke o])lique to the outer surface. The largest ventral valve 

 has a length of U mm., width 7 nun. Nothing is known of the interior 

 of the valves. The form, surface markings, and shell structure are 

 much like those of Oholus inatinalm and O. tetonen,ns. In outline 

 (>. shensiensis is more elongate than O. nudhutUx and less so than 

 (K tetonensis. 



Formation und locality. — Upper Cam])rian. Chao Mi Tien lime- 

 stone. Eight miles south of Ting Hsiang Hsien, and one mile south 

 of Chen Ping Hsien, Shensi, China. 



Collections of Bailey Willis and Elliot T. Black welder, Carnegie 

 Institution Expedition to China. 



OBOLUS TETONENSIS, new species. 



The general form, convexity, and appearance of this species is so 

 much like that of Oholu/^ matlnalis that a general description is 

 unnecessary. It varies from that species in the shorter, more trans- 

 verse dorsal valve, and the narrower outline of the ventral valve 

 toward the beak. 



This species occurs in great abundance in the thin-l)edded limestone 

 in the upper portion of the Cambrian section of the Teton Range, 

 Wyoming, in association with B'dlliKjHdla pep'tna and Oholu-s {Liiuju- 

 lepdn) acuminat'UH var. meekl. What appears to be the same species 

 occurs nearl}^ 700 feet lower in the section in a thin-bedded sandstone. 

 The dorsal valve from this horizon is broader and more transverse 

 posteriorly than the dorsal valve from the upper horizon. 



Formation and locality. — Middle Camln-ian, on the divide at the 

 head of Sheep Creek, near north end of the Teton Range, Wyoming. 

 Thin-bedded limestones. Belt Park, 6 miles out from Neihart, Mon- 

 tana. Three miles southeast of Malad City, Idaho, a smaller form, 

 collected by Dr. A. C. Peale in Bostwick Canyon, Bridge r Range, 

 Montana, ma}^ belong to this species. It occurs in a fine-grained 

 sandstone low down in the Paleozoic section. 



Dark gray limestone, Ophir City, Utah. 



