REPORT ON UPPER PALEOZOIC FOSSILS FROM CHINA. 299 



in the Ssi-ch'uan section with that which is next to the lowest, represented 

 by lots 1,2,3, 4, and 7. This fauna, containing as it does Schwagerina and 

 Notothyris, is clearly Upper Carboniferous, and well up. 



The three overlying faunas are too scanty to determine their age very 

 definitely. The greatest doubt surrounds the highest of these, that which 

 was found in a gray limestone lying upon the Red Beds 7 miles (11.2 km.) 

 south of Ta-ning-hien. From this horizon our collection affords only round 

 crinoid stems, Dielasma ? cf. D. elongatum, Aviculipecten ? richthofeni Girty, 

 and indeterminable fragments of pelecypods. 



The little pectinoid described as Aviculipecten ? richthofeni is of a type 

 which is common in the Paleozoic, and doubtless in the Mesozoic as well. It 

 has a somewhat related species in the Permian of Russia (Avicula kazanensis 

 de Verneuil) . The cardinal structures, and therefore the generic position, can 

 not be ascertained from our material. The terebratuloid cited as Dielasma ? 

 cf. D. elongatum has two large dental plates, but the structures of the dorsal 

 valve, which are usually more difficult to ascertain, have not been satisfac- 

 torily determined. I believe that it is not definitely known to what extent 

 Mesozoic terebratuloids develop plates in the ventral valve, but it appears 

 to be rather a peculiarity of Paleozoic shells. Upon this point Waagen says, 

 speaking of Hemiptychina: "The genus is distinguished very characteristi- 

 cally from the greater number of Paleozoic Terebratulae by the absence of 

 dental plates in the ventral valve. In this respect it approaches more closely 

 to Mesozoic forms, in which dental plates are nearly always absent." [Mem. 

 Geol. Surv. India, Palaeontologia Indica, Salt Range Fossils, vol. i, p. 361.] 

 It would appear from this that this type of structure is more common in the 

 Paleozoic, though not entirely confined to faunas of that period. 



The evidence upon which the horizon in question is referred to the 

 Paleozoic consists of the septiferous terebratuloid, the round crinoid stems, 

 and the general Paleozoic complexion of the meager fauna. It is inconclusive 

 and may not stand against any facts which strongly point to a Mesozoic age . 

 For this reason my assignment to the Carboniferous is provisional merely, 

 and should the necessity arise of changing to a younger period the readjust- 

 ment would entail no serious conflict of evidence. 



The fauna from Y6n-yi-ss'i, in Shan-si (lot 20), is very scanty and the 

 only significant species is the crushed terebratuloid which, if correctly identi- 

 fied as a Hemiptychina, would warrant placing this horizon also in the Upper 

 Carboniferous. 



The collection from station 69, in Shan-tung, I refer to the Upper Car- 

 boniferous with some reserve. From this point were obtained the following 



species : 



Chonetes sp. Squamularia cf. 5. perplexa McChesney 



Marginifera sp. Cleiothyridina ? sp. 



From the same vicinity and at about the same horizon von Richthofen 

 made a collection which Freeh listed in the following terms : 



