136 Proceedings of the Royal Physical Society. 



that we meet the peculiar Aye-aye, and find most of the 

 varieties of the Lemurs. Here, too, we meet with some of the 

 rarest birds, such as the Euryceros, the Atelornis, and others, 

 that delight in the lonely shades of the forest. Passing 

 through the rough paths which cross the forest here and 

 there, we often come upon exquisite pieces of scenery — an 

 open glade, a picturesque clearing, a w^ood-cutters' village; but 

 in the cold damp depths of the forest itself, the rank rotting 

 leaves and timbers, the constant drip drip, is gruesome in the 

 extreme, — one longs for light again and air. 



Geology. 



This vast island, with its low country, its undulating 

 heights, its central plateau, is composed entirely of granite 

 basalt, and other volcanic rocks. From the highest peak of 

 Ankaratra down to the sea shore, there are but few traces of 

 sedimentary rock. Inland from the lakes a few miles, there 

 is a bed of dark clay, in which are many marine shells ; thirty 

 miles inland there is a stratum of flint — but these form the chief 

 exceptions in such parts of the island as are well known to 

 us. It was only when travelling towards the south-west, 

 almost at the extreme western verge of the Bara land, that I 

 came upon sedimentary rock in any quantity. The hills 

 around Lake Itasy, and the numerous hot springs in different 

 parts of the country, show that Madagascar was at one time 

 the scene of much volcanic activity. Many of the hill-sides 

 are composed of decaying granite, and to the south in Betsileo 

 there is evidence of currents having at one time denuded 

 the eastern side of most of the hills. 



Madagascar and the Mascarene islands are \vithout doubt 

 the remains of a former continent, which at one time 

 occupied this part of the Indian Sea, but as to whether it was 

 at any time connected with Africa or Southern India, is a 

 question of extreme difficulty. 



In relation to the formation seen, but not properly examined, 

 in the western Bara, the Isalo hills appeared to belong to the 

 sedimentary formation, and to have skirted wliat was at no 

 distant date a lake of considerable size, the water markings in 

 terraces being quite distinct along the eastern side. On the 



