330 Reviews — Ordovician and Silurian Fossils, Yun-nan. 



I. — Ordovician and Silurian- Fossils fkom Ypn-nan. By F. R. 

 CowPER E.EED, M.A., Sc.D., F.G.S. Palaeontologia Indica, n.s., 

 vol. vi, Memoir 3, pp. iv + 69, 8 pis., 1917. 



SINCE 1913 we have known that Mr. Coggiu Brown, during liis 

 exploration of Soutli-western Yun-nan a few years previously, had 

 collected some Lower Ordovician and Silurian fossils. Dr. Cowper 

 Reed's complete description of these is at last published, with 

 excellent illustrations by Mr. T. A. Brock, and with determinations 

 of the graptolites by Dr. Gertrude Elles. 



The Ordovician fossils are from three localities : Pu-piao, La-meng, 

 and Shih-tien. It was from Pu-piao that Loczy on the Szechenyi 

 expedition obtained cystid plates referred by him to Semicosmites. 

 The rocks here are mudstones with a calcareous band ; all are 

 probably of Llandeilo age, and the mudstones, at any rate, contain 

 Didymographis murchisoni and its normal associates. Tlie rock at 

 La-meng resembles that of the Hwe Mawng Beds in the Northern 

 Shan States of Burma, and the few poorly preserved fossils are 

 consistent with that horizon. Five types of rock from Shih-tien 

 probably represent as many beds. The contained fossils show 

 general agreement with the fauna of the Sedaw Beds in the 

 Naungkangyi series of the Northern Shan States, and Dr. Reed 

 inclines to correlate the beds with Schmidt's stages B and C 

 ( Orthoceras, Echinosphcera, and Chasmops Limestones) of the Baltic 

 region. 



The Silurian beds of Shih-tien consist of two kinds of shale, with 

 two different assemblages of graptolites of Llandovery age. Tlie 

 higher horizon belongs to the base of the zone of Monograptus 

 sedgtvicki, and its most abundant fossil is M. hhifems. The lower 

 horizon abounds in CUmacograpti, not specifically determinable, witli 

 other specimens suggesting the zone of Orthograptus vesiculosus or 

 the base of the Ifojiograptus gregarius zone. These two horizons 

 yield no fossils other than graptolites. 



Of the Ordovician fossils the most important are the Cystids,. in 

 respect to number both of specimens and of species and in respect to 

 novelty, there being described two new genera and ten new species. 

 The genera are Sinocystis and Ovocystis (n.gg.), Pyrocystis, 

 Eucystis, Splueyonis, Echmosphcera, Seliocrinus, Caryocystis, 

 Echinoencrinus, and Caryocrinus. Crinoids are represented only 

 by one specimen of the fossil which Dr. Reed calls Camarocrinus 

 asiaticus. Of Brachiopods there are the genera : Philhedra (1 n.sp.), 

 Orthis (1 n.sp.), Hemiproiiites (1 n.var.), Rafinesqui7ia{?), Plectam- 

 loniies, Streptis, and Poramhonites. Laznellibranchs are represented 

 by undetermined species of Ctenodonta and Conocardium ; and Gastro- 

 pods by doubtfully determined species of Holopea, RapMstoma, 

 £eUeropho7i, Cyrtolitina, and Hyolithes. Cephalopods are numerous, 

 especially at Shih-tien, and belong to Endoceras, Orthoceras (1 n.sp.), 

 Jovellania, Cameroceras (?), Actinoceras, Spyroceras (?), IVochoUtes 

 (1 n.sp.), Lituites, SiMtXTarphyceras (?). The few and often fragmentary 

 remains of Trilobites are referred to Harpes, Remopleurides, Asaphis, 



