Upper Palceozoic Shells from Madagascar. 7 



elongate nodule, associated with one of the fish-fragments ; 

 and (2) a series of minute pelecypod valves crowded together 

 in a similar but smaller nodule and of more oval shape, 

 which apparently belong to one species. The gastropod 

 seems to be easily determined as a form of Planorbis, whilst 

 the bivalves may be referred to the genus Naiadites of 

 J. W. Dawson, originally described from the Upper Car- 

 boniferous rocks of Nova Scotia. 



So far as can be ascertained, no Planorbis has been 

 recorded from rocks older than the Lias, Charles Moore 

 having described a species from the lower part of that 

 formation together with other freshwater mollusca which 

 had been found in the Mendip country of England (Quart. 

 Journ. Geoi. Soc. 1867, vol. xxiii. pi. xv. fig. 10, p. 548). 

 Strange to say, the affinities of the Malagasy shell appear 

 to resemble the well-known modern form of Planorbis 

 carinatus of M tiller, on account of its possessing, among its 

 other characters, a peripheral carination, the presence of 

 which would place it in Stein's genus Tropidiscus (established 

 on the Miiller shell just mentioned), but for present purposes 

 it is, perhaps, advisable to recognize the specimen under the 

 more popular name of Planorbis. 



The occurrence of Naiadites is also of considerable interest, 

 since it assists in confirming the view that these fossiliferous 

 nodules are of Upper Palaeozoic age. It is only quite 

 recently that Palaeozoic fossils have been discovered in 

 Madagascar by Captain Colcanap, of the French army. 

 Previously, Professor Marcellin Boule had remarked on a 

 series of sandstones, conglomerates, and schists forming the 

 base of the sedimentary series in that country, which reposed 

 on the crystalline rocks and extended with them from north 

 to south of the island. Apparently unfossiliferous, with 

 the exception of silicified trunks of trees which had never 

 been satisfactorily determined, these deposits were regarded 

 as of Triassic age, being compared with the Karoo formation 

 of South Africa and the Gonclwana Series of India ("La 

 Geologie et la Paleontologie de Madagascar": Congres 

 Geologique International, viii. session, France, 1900 [Paris 

 1901], p. 5, pi. xii. = Geological Map of Madagascar). 

 When the new material from Capt. Colcanap was examined, 

 Professor Boule was able to announce the discovery of a 

 Permian fauna and flora as well as coal deposits in the 

 Mahafaly district of the south-western part of the country — 

 forming part of the supposed Tiiassic rocks previously 

 mentioned, — including remains of reptiles, fishes, and 

 Glossopteris ; the latter determined by Professor Zeiller as 



