DESCRIPTIONS OF NEW SPECIES OF ORDOVICIAN 

 FOSSILS FROM CHINA. 



By Stuart Weller, 



Of the University of Chicago, Chicago, Illinois. 



The following" new species of Ordovician brachiopods and trilobites 

 were collected by the members of the Carnegie Institution Expedition 

 to Eastern Asia in 1903—1:. They are all from the Ki-sin-ling lime- 

 stone at two localities near Su-kia-pa, in the province of Ssi'-ch'uan, 

 China. Locality 20 C is in a g-idch just northeast of Su-kia-pa, while 

 locality 20 B is at the narrows of the Ta-ning- River 1^ miles above 

 the same place. The formation from which the fossils were secured 

 is a dark, massive limestone 3,500 feet in thickness lying comformably 

 upon subjacent l)eds of Cambrian age. The fossils are all from the 

 uppermost layers of the formation, and in age are approximately 

 equivalent to the fauna of the Trenton limestone of North America. 



The types of the new species here described will be deposited in the 

 United States National Museum on the completion of the forthcoming 

 report of the Expediti,on to be published by the Carnegie Institution, 

 in which work also illustrations of all the species will appear. 



Order BRACHIOPODA. 



PLECTORTHIS WILLISI, new species. 



Deserq)t!on. — Shell transversely subelliptical in outline, the hinge 

 line a little shorter than the greatest width, cardinal extremities 

 slightl}' rounded. Pedicle valve depressed-convex, slightly com- 

 pressed toward the cardinal extremities; the beak small, scarcel}^ 

 incurved, cardinal area a little concave, sloping backward from the 

 plane of the valve; cardinal margins angular. Brachial valve nearlj^ 

 as convex as the pedicle, compressed toward the cardinal extremities. 

 Surface of each valve marked by from twenty to t\vent3-tive major, 

 radiating, rounded costi«, whiclx increase in width conspicuously in 

 passing from the beak to the front margin; in each interspace between 

 these major costa? from one to three smaller ones which do not reach 



Proceedings U. S. National Museum, Vol. XXXIl— No. 1 549. 



557 



