REPORT ON UPPER PALEOZOIC FOSSILS PROM CHINA. 325 



four of these are developed as plications of the shell, the remainder appearing on 

 the margin as denticulations. Even these four, however, are obscure, and decrease 

 in intensity in proportion to their distance from the sinus. 



The dorsal valve is subcircular in outline, highly gibbous. The beak is small, 

 pointed, slightly prominent. There is a strong, deep, ill-defined mesial sinus, which 

 projects in front as a sort of linguiform extension corresponding to a deep emargi- 

 nation of the front of the opposite valve. The sinus, which dies out long before 

 reaching the hinge-line, is subdivided by a strong mesial fold, extending about as 

 far from the edge as the sinus itself, and each of the two channels thus formed is 

 apparently again subdivided by an obscure plication limited to the marginal region. 

 On each side of the sinus there are about six plications, shown rather by denticula- 

 tions at the edge of the shell than by folds upon its surface. 



Internal structure unknown. Shell strongly and finely punctate. 



As only a single specimen of this form was found it was impracticable to muti- 

 late it for the purpose of ascertaining its internal structures; therefore the generic 

 position of the species is somewhat conjectural. The shell structure and configura- 

 tion consign it at once to the Terebratulidse, and in the character last mentioned 

 it much more closely resembles the genera NoMhyris and Hemiptychina than the 

 plicated Dielasmata. It is somewhat uncertain whether this fossil should be regarded 

 as having a dorsal sinus in which a mesial rib has been developed, or a dorsal fold 

 with two deep channels upon its sides; but the former interpretation seems to be 

 more natural. Upon that view the species under consideration would be one of 

 the antiplicati, and its generic position would be with NoMhyris in preference to 

 Hemiptychina. On one side of the specimen may be noticed an appearance similar 

 to that often observed in Dielasma when fracture or cleavage takes place along the 

 dental plates, but in the present case this may be due to exfoliation of the thick 

 shell. Of course the presence of dental plates would debar this form from Notothyris 

 and Hemiptychina alike. 



In its specific relations this form differs sufficiently from any of the species 

 whose descriptions have come into my hands to make a detailed comparison unneces- 

 sary. It is perhaps as near as any to N. inflata Waagen and N. djoiilfcnsis Abich. 



Locality and Horizon. Pennsylvanian (Wu-shan limestone) ; near L,iang-ho-k'6u, 

 East Ss'i-ch'uan (station 7). 



Schizodus cf. S. curtus Meek and Worthen. 

 Plate 29, Figure 27. 



This species is represented by three or four specimens preserved as molds of the 

 interior. The shape and dentition are those of Schizodus, and the specific characters 

 indicate an affinity with a little shell figured by de Verneuil as 5. rossicus var. and 

 also with our American species 5. curtus. The width is 9 mm. and the height some- 

 what less, about 8 mm. The general shape appears to have been subcircular, but 

 with the posterior portion of the basal outline straightened and with a long posterior 

 truncation directed toward it at something less than a right angle. The beak is not 

 very prominent, but makes a distinct projection in the outline. In some cases the 

 umbonal ridge seems to have been well marked, in others more obscurely marked. 



One would hardly venture to identify this form directly with 5. rossicus, but it 

 is very similar to a specimen figured by de Verneuil under the title of 5. rossicus var. 1 

 It differs, however, in having a less transverse shape, a sharper inferior-posterior 

 angle, and a less strongly inclined truncation. Though closely similar to N. curtus, 

 it seems to differ from some of Meek's figures in having a less prominent and pro- 



'Murchison, de Verneuil, and Keyserling, Geology of Russia and the Ural Mountains, vol. 2, 1845,- 

 pt. 3, plate 19, fig. 8. 



