324 RESEARCH IN CHINA. 



plates as well developed nor the beak as large as the present example. As the dorsal 

 valve is unknown, the generic position of the Chinese shell can not be completely 

 determined, but it is more probably a Dielasma than one of the other related Car- 

 boniferous terebratuloids. 



Locality and Horizon. Pennsylvania!! ; near Ts'ai-kia-chuang, Shan-tung (sta- 

 tion 59). 



Hemiptychina ? aff. H. orientalis Tschernyschew. 

 Plate 29, Figure 21. 



Of this species our collection contains a specimen which has been somewhat 

 crushed and distorted by compression. The length is 1 1 mm. and the width 9 mm. 

 The shape is subpentagonal. The widest point is about midway; from there the 

 gently convex cardinal slopes contract posteriorly and the nearly straight sides 

 approach the front in an almost parallel direction. The front is subtruncate, nearly 

 straight across the middle, and somewhat abruptly rounding to meet the sides. 

 The ventral valve possesses a strong, broad sinus, which extends only a short distance 

 back from the margin, and the dorsal valve also seems to possess a faint, narrow sinus 

 in the same region. Owing to the present condition of the specimen, the presence 

 or absence of marginal plications can not be determined, and, indeed, many details, 

 both of configuration and structure, may be obscured. 



In the dorsal valve two septa are clearly shown, while a third may probably be 

 inferred from the fact that one of these seems to have a nearly median situation in 

 the valve, which has slipped considerably to one side in relation to its fellow. In 

 the ventral valve no dental plates seem to be present, even upon the side which 

 has suffered but little from crushing, and since these structures are retained in the 

 similarly injured dorsal valve it appears probable that they were really absent. 

 The specimen therefore must be referred to the genus Hemiptychina, nor is an unpli- 

 cated species alien to the genus, for in H. sublavis Waagen we have one in which 

 plication is faint or missing. In H . orientalis Tschernyschew the folds are large and 

 few, and to this species the present form appears to be more essentially related than 

 to that in which they are more faint but fine. 



If the present form does really possess dental plates, then it is without much 

 doubt a Dielasma and is related to a number of species in both hemispheres. 



In addition to the specimen from which the foregoing description was drawn up, 

 one very fragmentary example from station 20 has been assigned to the same group. 

 Its specific characters have been lost, as the specimen is quite fragmentary ; but the 

 apparent absence of dental plates in the ventral valve, which is the only portion 

 retained, would seem to indicate that the genus is Hemiptychina. 



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

 East Ssi-ch'uan (station 7). Pennsylvanian; Y6n-yi-ssi, Shan-si (station 20). 



Notothyris willisiana Girty. 



Plate 29, Figures 18-20. 

 Notolhyris willisiana GIRTY, 1907, Proc. U. S. Nat. Mus., vol. xxxin, i>. 46. 



Shell small, subspherical. Ventral valve subovate, gibbous, rapidly and rather 

 suddenly contracting at the beak, which is strongly deflected and truncated by a 

 relatively large foramen. Toward the front this valve is marked by a narr,\. 

 moderately strong but shallow sinus extending about half the length. There should 

 be other modifications of the mesial portion to correspond with the plications on 

 the accompanying valve, but if present they are obscured in the typical specimen. 

 On each side of the sinus traces of some six or seven ribs arc found. Only about 



