34 SANDSTONE. 



and from a drawing he gives of tliem appear to belong to the 

 Neocomian formation, and are species of the genera Ammonites, 

 Terebratula, Nerinea or Turritella, Einoceramus, and Eliyn- 

 conella, together with an Echinodcrm. 



It is evident, also, that there are deposits of a much later 

 date than the above, for in the south-west of Madagascar M. 

 Grandidier discovered the fossil remains of a hippopotamus (a 

 pachyderm not now found living in the island), of gigantic 

 tortoises (which are now only found in the little island of 

 Aldebra to the north of Madagascar), and of the probably 

 very recently-extinct struthious bird, the yEpyornis maximus, 

 whose egg (12^ in. X9|^ in.) so far exceeds that of any other 

 known bird. It seems highly probable, therefore, that a 

 systematic examination of these less elevated portions of 

 Madagascar would reveal the existence of much that is in- 

 teresting and valuable both in paleeontology and geology, and 

 so light would be thrown upon many problems connected 

 with the anomalous animal life of the country and of neigh- 

 bouring islands in the Indian Ocean. It is evident that 

 these maritime plains were under water during portions at 

 least of the Secondary period, at which epoch the high grani- 

 tic region alone formed the island of Madagascar, then a 

 country probably only a third of its present extent.* 



Dr. Auguste Vinson speaks of seeing yellow sandstone on 

 the eastern coast, and he also describes the plain between 

 the two eastern lines of forest as being composed of beds 

 of sedimentary formations, " rich in fossil remains." Unfor- 

 tunately he gives no particulars as to these alleged extinct 

 organisms, so we are still in the dark as to the geological 

 age of these formations. In sailing down the river B^tsiboka 

 to the north-west coast, I noticed at one point that for a con- 

 siderable distance the river bank was formed by layers of 

 yellowish sandstone closely resembling a wall of masonry. 

 Some of the courses appeared much weathered, while others 

 had a smooth face, as if of much harder material. 



* This is confirmed by what is said in a "Notice sur une Exploration Gdolo- 

 inr[ue de Madagascar, par M. Ed. Guillemin," in Annales des Mines, 6ine s^rie, 

 t. X., 1806, pp. 277-319, who speaks of fragments of basalt being found far 

 from the sea, at the foot of the mountains and many metres above the sea-level, 

 with sea-shells, apparently of a recent date, attached. 



