CAMBRIAN FAUNAS OF CHINA— WALCOTT. 567 



ture. ■ The exterior surface appears smooth under a lens of moderate 

 power, but with a strong lens it is found to be perforated by minute 

 pores; the interior surface is marked 1)}^ arching- ridges, radiating 

 from the base toward the outer edge, connected by transverse ridges, 

 between which rounded pits occur. A diagonally transverse thin sec- 

 tion shows the system of ridges described and the openings between 

 them. The same section cuts across near the base of a cup. In this 

 the calcite is so crystallized that no definite structure, with the excep- 

 tion of a few traces of septa extending from the inner wall to the 

 outer wall, can })e distinguished. 



The fragment illustrating the interior wall indicates a cup that 

 expanded much more rapidly than the cup described above. It may 

 be that a second species is indicated by this, but with the material 

 available for study it does not appear best to attempt to distinguish 

 them by applying distinct names. 



When the surface of the outer wall is slightly worn the radiating 

 lines and transverse septa are very clearly shown. 



Ohservations. — The generic reference to Cos&mocyathus is made on 

 account of the presence of the regular cross septa in addition to the 

 radial septa, as defined b}- Dr. J. G. Bornemann." None of the Sibe- 

 rian forms of the Archseocyathmx described by Dr. Pxluard von Toll^ 

 appears to be closely related to this species. 



The specific name is given in recognition of the work of Miss Elvira 

 Wood in the preliminary study of the Cambrian fauna of China. 



Formation, and Jocallty. — Middle Cambrian, in a brownish gray, 

 partly oolitic limestone, in a liorizon corresponding to the lower por- 

 tion of tlie Ch'ang-hia formation of Shan-tung; 4.5 miles south of 

 Wu-t'ai-hien, Shan-si, China. 



Collected by Eliot Blackwelder. 



BRACHIOPODA. 



Genus OBOLUS Eichwald. 



LINGULEPIS Hall, subgenus of OBOLUS, 



OBOLUS (LINGULEPIS?), species undetermined. 



This species is represented by a few fragments, one of which shows 

 that the ventral valve is elongate, and the apex acuminate. The shell 

 was built up of several layers or lamellge, as in characteristic forms of 

 Oholus and its subgenera. The interior surface of some of the lamellae 

 is marked by fine, radiating, and concentric strige; the outer surface, 

 under a strong magnifier, shows fine, concentric, somewhat irregular 

 strife. 



«Deutsch. geol. Gesell. Zeitsch., XXXVI, 1884, p. 704. 



i'Mem. de I'Aead. Imp. des Sciences de St.-Petersb., 8th ser., VIII, No. 10, 1899. 



