REPORT ON UPPER PALEOZOIC FOSSILS FROM CHINA. 319 



The characters of the present shells, so far as known, are more like a group of 

 species occurring in the American upper Devonian and lower Mississippian rocks 

 than any which are known to me from the Upper Carboniferous. The peculiarities 

 especially in mind are the low, broadly rounded or angular ribs and the absence 

 of regular, fine, distinct, concentric crenulations; instead of the latter only faint 

 incremental lines appear to be present. 



Locality and Horizon. Pennsylvanian (Wu-shan limestone) ; Tung-kuan-k'ou, 

 East Ss'i-ch'uan (station 17). Pensylvanian : near Ts'ai-kia-chuang, and near Yen- 

 chuang, Shan-tung (stations 59 and 69). 



Productus ? sp. 



Plate 29, Figures 14, 15. 



This unusual form is represented by three specimens, each from a different 

 locality. They show certain differences, which are regarded as being due to age 

 and will be considered below. 



The smallest example has a width of 3 mm. and a length somewhat less. The 

 shape is semielliptical, perhaps contracting a little at the hinge. The cardinal angles 

 were probably quadrate. The shell is nearly flat and the only ornamentation con- 

 sists of fine, sharp concentric wrinkles, of which there are eight. This specimen has 

 the appearance of a very young Productus. The concentric wrinkles in their sharp- 

 ness and regularity somewhat suggest Leptccna rhomboidalis, but the fine ribs of that 

 species are not present. 



Another example has a width of 9 mm. and a length of about 7 mm. The 

 cardinal angles are quadrate, the hinge-line straight, and the antero-lateral outline 

 regularly rounded. The convexity is low, the ears somewhat flattened, the beak 

 small and depressed. The general shape is that of a young dorsal valve of Productus. 

 The surface is marked by regular, fine, strong concentric wrinkles, 15 in number, 

 increasing greatly in size with the dimensions of the shell. Toward the margin fine 

 concentric striae can be made out. The mesial area is, furthermore, marked by 5 or 

 6 relatively coarse, somewhat obscure ribs, which are not so strong as the wrinkles 

 with which they decussate. The more rostal portions of this specimen possess the 

 same characters as the small example first considered. 



The third example is similar to that just described, except that it is a little 

 larger and the wrinkles are a little coarser. 



This shell possesses the general appearance of Productus, but the sculpture, 

 when considered closely, is unusual for that genus. Among our American Carbon- 

 iferous species I recall nothing comparable to it, and of species of foreign description 

 and occurrence but very few. It resembles to some extent P. plicatilis Sowerby, 

 which Kayser identifies from Tshau-tien, but differs both from his and from David- 

 son's figures of that species. A certain amount of similarity can be traced also to P. 

 undatus de France and to P. carringtonensis Davidson, as these species are recognized 

 by Kayser and figured in his report. But it is not possible to identify my material 

 with either. In point of being without radial ornamentation, except over a differen- 

 tiated mesial portion, this form suggests Productus mesolobus as figured by Davidson 

 from England and by Murchison, de Verneuil, and Keyserling from Russia. If a 

 Productus at all it would perhaps belong to the group represented by P. mesolobus, 

 though without question belonging to a distinct species. 



Although its characters are such as almost certainly to entitle the present form 

 to recognition as a new species, no name has been proposed for it, both because it 

 is imperfectly known and because of the uncertainty which surrounds its generic 

 relations. 



