NO. 1395. CAMBRIA N BRA CHIOPODA— WALCOTT. 329 



The interior of the ventral valve shows that the area is short and 

 divided midway by a narrow pedicle furrow that merges into the vis- 

 ceral area, which extends forward about one-third the length of the 

 valve; on each side of the anterior central portion of the visceral area 

 there are two small trapezoidal areas within which the central scars and 

 the middle and outside lateral muscle scars were attached ; the small trans- 

 median and antero-lateral muscle scars are situated close to the main 

 vascular sinus opposite the anterior portion of the central visceral 

 area. A partial cast of the interior of the dorsal valve shows a rather 

 wide visceral area with the antero-lateral scars about the center of 

 the valve and the central scars about one-fourth of the distance back 

 from the center to the posterior margin. Of the impressions left by 

 the vascular system only the main vascular sinuses of the ventral valve 

 have been seen; these are situated about midway between the central 

 visceral area and the margins of the valve. 



Observations. — This species occurs abundantly in association with 

 Acrotreta shantu/Kjensis. It is closely related in form to O. {Lmgii- 

 lella) prlndell of the upper Olcnellus zone of eastern New York, and 

 belongs with a group of small shells that have a wide vertical and 

 geographical range, as is noted under the description of (>. L. prindeli. 

 With the data availal)le for comparison it differs from O. L. prmdcU 

 in its shorter cardinal area and visceral area in the dorsal valve. 

 From 0. {L'mgaleUa) daniesi it differs in being broader in proportion 

 to its length. 



Formation and locality. — Middle Cambrian. Chang llsia limestone. 

 Two and one-half miles south of Yen Chuang, on NNE. spur of Hu 

 Lu Shan, China. 



Collected by Mr. Eliot T. Blackwelder, of the Carnegie Institution 

 Expedition to China. 



' OBOLUS (LINGULELLA) DAMESI, new species. 



The general descriptions of O. L. ehinensis and <). L. pri/zn/s apply 

 so closely to this species that it does not appear necessary to do more 

 than call attention to the points in which they differ. From 0. L. 

 ehinensis this species varies in having a more elongate, acuminate 

 ventral valve and ovate dorsal valve; the valves are also less convex. 

 From 0. L. primus it differs in the more gradual curvature of the 

 sides from the apex to the front margin, in this respect resembling 

 some varieties of O. L. ferrmjineous. The average size of the ventral 

 valve is about 5 mm. in length by 3.5 mm. in width. 



The species is named after Dr. Wilhelm Dames, who first described 

 the Cambrian faunas of China. 



Formation and locality. — Middle Cambrian. Chang Hsia limestone. 

 About 3 miles southwest of Yen Chuang, Shan Tung, China. 



Collected by Mr. Eliot T. Blackwelder, of the Carnegie Institution 

 Expedition to China. 



