320 RESEARCH IN CHINA. 



Locality and Horizon. -Pennsylvania!! (Wu-shan limestone) ; near Ta-ning-hien 

 (stations 3 and 4) and near Liang- ho-k'6u (station 7), East Ssi ch'uan. 



Marginifera ? sp. 

 Plate 29, Figures 12, 13. 



This species is represented by three specimens, all ventral valves, which, though 

 differing from one another in certain respects, are yet so imperfectly preserved that 

 it seems inadvisable to separate them. 



The size is small, the greatest width probably varying from n to 15 mm. in 

 different specimens. The shape is subquadrate. The visceral area is somewhat 

 flattened and gives onto the lateral portions rather suddenly. The sinus is faint 

 or absent. The beak appears to be small and to project but little beyond the hinge. 

 The ribs are fine, about six or eight in 3 mm., rounded and moderately strong. They 

 are fainter over the visceral area, especially toward the beak, and over this area they 

 are crossed by equally fine, regular, but not very distinct concentric wrinkles. A 

 few small spines are scattered over the front and sides, and possibly the visceral area, 

 and probably the ears were also similarly supplied. 



This poorly characterized type has others similar or identical with it in many 

 Upper Carboniferous faunas. Among those of North America Marginifera u-abash- 

 ensis and M. ingrata may be mentioned, from the one of which it differs in its 

 smaller size, finer and more distinct ribs, and absence of a sinus, and from the other 

 in being smaller and more finely ribbed. It resembles Productus longispinus as 

 identified by Kayser among Chinese specimens, especially the small, or as he calls 

 it the American, variety. His figures show a deeper sinus than there is evidence 

 of in the examples before me. From typical P. longispinus the latter are with little 

 doubt distinct. It may be recalled that Waagen concluded that P. longispinus is 

 not a Marginifera, the characteristic structures of which are certainly found in the 

 American species mentioned. 



It can not be determined whether the present form is a Productus or a Margin- 

 ifera, but the superficial resemblance is especially with species of the latter group. 



Locality and Horizon. Pennsylvanian, near Yen-chuang, Shan-tung (station 69 ) . 



Spirifer blackwelderi Girty. 



Plate 29, Figures 16, 17. 

 Spirifer blackwelderi GIRTY, 1907, Proc. U. S. Nat. Mus., vol. xxxni, p. 45. 



This form has been obtained at two localities, and occurs in considerable abun- 

 dance as casts of separate valves. The following characters have been observed: 



The shape of the ventral valve is subquadrate. The convexity is high, the 

 beak large, erect, gibbous. The area is well defined, high, and concave. The fora- 

 men is large, its width at the base being almost one-third that of the whole area. 

 The cardinal angles are rounded and the cardinal line considerably shorter than the 

 greatest width. A narrow and moderately deep sinus traverses the shell, becoming 

 gradually broader and less well defined toward the front. The sinus is not divided 

 by plications, nor do any ribs mark the sides. On the interior there are two strong 

 dental plates, but no septum. 



The dorsal valve is transversely subelliptical in outline. The cardinal extremi- 

 ties are rounded and the hinge-line is shorter than the greatest width. The beak 

 is small and depressed. A moderately high, rather well defined mesial fold passes 

 downward, gradually widening in its course. 



