92 BOCKS AND POSSILS FROM MADAGASCAR. [Feb. 1 89 5. 



Discussion (on the two preceding Papers). 



The President pointed out that while many of the missionaries 

 in Madagascar had paid attention to the Quaternary deposits of that 

 island, and had sent home numerous remains of many species of 

 gigantic wingless birds (like the Dinornis in New Zealand), Mr. Baron 

 had, in his former and present communications to the Society, made 

 us acquainted with a series of formations and fossils extending from 

 the Jurassic to the Tertiaries ; and, thanks to Mr. B. B. Newton, the 

 fossils from these several deposits had all been identified and named. 

 Mr. Baron had further shown that there were volcanic rocks and 

 evidences of old volcanic action. He had shown that some of the old 

 lake-basins were also connected with hot springs and volcanic vents. 

 In these dried-up or partly dried-up lakes vast deposits of bones had 

 been observed by Mr. Baron and by other missionaries — principally 

 bones of JEpyornis, Hippopotamus, Palceolemur, Testudo, and Croco- 

 dilian bones. Mr. Baron was fortunate in having Mr. Newton to 

 examine and name the fossils which he had so successfully collected. 



Dr. Dtt Biche Preller pointed out that close to the rock 

 termed ' foyaite ' by Mr. Baron appeared nepheline-phonolite, which 

 latter is simply a younger form of foyaite, and that the association 

 of both bears close analogy to the foyaite or elaeolitic syenite of 

 Southern Portugal. The latter outcrop occurs in Jurassic strata, 

 and hence the inference is justifiable that the area in which foyaite 

 and phonolite occur in the North-west of Madagascar, and which 

 the Author marks ' unknown,' is also Jurassic. 



Dr. J. W. Gregory remarked on the close and interesting analogy 

 between this area, the Peninsular region of India, and the main- 

 land of Africa. The gneiss seemed to resemble that which forms 

 the whole tableland of East Africa, and is covered by volcanic rocks 

 of the same types. Probably in Madagascar occurs the same 

 sequence from trachytes to andesites and basalts as can be demon- 

 strated on the mainland. The occurrence of ancient lake-basins of 

 vast area is another resemblance to East Africa. The association of 

 the volcanic rocks with marine sediments is of value, as it may help 

 to determine the age of the volcanic series of British East Africa. 

 The map seems to confirm that issued by Cortese about six years ago. 



Mr. W. W. Watts stated that a large number of Mr. Baron's slides 

 had passed through his hands, and he could testify to the thorough- 

 ness of the Author's work and the care which he had devoted to hi3 

 determinations. He called attention to the resemblance between 

 the rocks of the gneissose area and those of the North-west Highlands. 

 In reply to Dr. Preller, he said that he had not seen Mr. Baron's 

 foyaite, but he had seen the phonolites and haiiyne-rocks. Knowing 

 what we do of the eruption of rocks of similar composition in 

 widely different ages, he thought it would hardly be wise to map an 

 area of rocks as Mesozoic, merely because they happened to be 

 penetrated by a boss of foyaite. 



Mr. W. H. Hudleston also spoke, and Mr. B. B. Newton replied 

 for his paper. 



