139^ 



species oiTcntaciilitcs, which especially belong to' the group of T. ornattis Sow. 

 One form is characterized by having sharp rings of equal elevation, o. i 5 mm. 

 apart on the average, and smooth internodes. The other is distinguished 

 from it by having the rings, more crowded and of two different magnitudes, 

 the thicker ring appearing in alternation with one or two weaker ones which 

 are set at rather irregular intervals. 



So far as we are aware, there is at present nO' record of the occurrence of 

 Pteropoda limestone in the Chinese provinces ; from Indo-China, however, 

 Mansuv has reported a Pteropoda limestone from the district of Cu-le, which 

 contains Styliola cfr. clavuhis Barr.^^ The present forms resemble this 

 species in form and size, but are certainly Tuitacu/itcs and not Styliola, being 

 provided with numerous sharp rings. Mansuy also found Tcntaatlitcs cfr. 

 szibcochlcatus''^ Tciitaciditcsl sp.^Mn another Pteropoda limestone from 

 Pien-Doc. These two forms are considerably larger than the Chinese 

 fossils now at hand, and show a different sculpture. The two Pteropoda 

 limestones from Indo-China are Lower Devonian in age.** 



Locality : — Shuang-chin-tang, Tao-chou, Yung-chou-fu, prov. Hu-nan 

 (NoDA Coll. No. 58.) 



Geological age : — No other fossils being found in the rock, its geological 

 age depends solely on the present fossils ; Tentaailitcs being a genus ranging 

 from Ordovician to Devonian, and especially abundant in Gotlandian and De- 

 vonian, I prefer provisionally to assign this Tcntaatlitcs limestone to the De- 

 vonian age, since we have at present no record of the development of rocks 

 older fhan Devonian in Yung-chou-fu. 



1) H. Mansuy: Contribution a la carte geologique de L'Indc-Chine, Palcontologie. 1908 p. 

 53, pl. XIII., fig. II. 



2) H. Mansuy: I.e. p. 53, pi. XIII., fig. 9. 



3) H. Mansuy: I.e. p. 53, pi. XIII., fig. 10. 



4) J. Deprat: Les series stratigraphiques en Indc-chine et au Yun-nan. Mem. Serv. Geol. 

 L'Indo-chine, vol. II., fase. II., p. 71. 



