FOSSILS. 33 



extensive elevated region of Madagascar is very ancient land, 

 and has probably remained for many ages above the waters 

 of the Indian Ocean ; otherwise some trace of marine deposits 

 would surely be found in portions of this great extent of 

 country. I may, however, here note the fact that there are 

 in some places such rounded boulder-like masses of blue 

 basalt rock, sometimes on the surface, and sometimes partially 

 embedded in the soil, that did these occur in the temperate 

 region one would certainly ascribe them to glacial action ; 

 but the point requires fuller investigation, and possibly some 

 other solution may be given to the rather puzzling inquiry 

 suggested. But in travelling to the north-west coast, as we 

 got near the sea-level on the banks of the Be'tsiboka, we met 

 with rounded boulders composed of rock which certainly does 

 not exist in situ anywhere near the spot where these boulders 

 occur, but has come from far away in the interior. 



With regard to the lower region of Madagascar — the 

 extensive plains to the west and south of the island, as well 

 as the narrower extent of country on the east coast — we have 

 a little more definite information as to the geology of some 

 portions of it. This division of the country is at a much less 

 elevation above the sea, being only as many hundreds of feet 

 above it as the granitic region is tlwusands of feet. Here 

 we find not only deposits of the later Tertiary epochs, con- 

 taining fossils of animals but recently extinct, but also fossils 

 of the Secondary age. This fact was first pointed out by 

 M. Grandidier, who, in speaking of the south and west 

 portions of the country, says : " Nerinca and other charac- 

 teristic fossils of the Jurassic formation which I have there 

 collected prove the existence of Secondary strata which cover 

 a vast extent of this island " {Bull, de la Soc. de G-eog., Aout 

 1871, p. 88). In a later number of the same publication 

 (Avril 1872) he also speaks of an extensive "terrain num- 

 mulitique parfaitement characterise - par des Neritina schmi- 

 deliana, et p^tri de foraminiferes appartenant aux genres 

 Alveolina, Orhitoides, Triloculina," &c. This is confirmed by 

 the fossils discovered in the south-west of Madagascar, in the 

 upper part of the valley of the St. Augustine Biver, by the 

 Bev. J. Bichardson in 1877. These occur in vast numbers, 



c 



