CHAP. XIX THE MADAGASCAR GROUP 432 



concerned, there is nothing but what is easily explicable 

 by what we know of the general means of distribution of 

 these animals. 



We now come to the Amphibia, which are represented 

 in the Seychelles by two tailless and two serpent-like 

 forms. The frogs are Rana mascareniensis found also in 

 Mauritius, Bourbon, West Africa, and Abyssinia, and 

 probably all over tropical Africa ; and Megalixalus 

 seychellensis a peculiar tree-frog having allies in Mada- 

 gascar and tropical Africa. It is found, Dr. Wright in- 

 forms me, on the Pandani or screw-pines ; and as these 

 form a very characteristic portion of the vegetation of the 

 Mascarene Islands, all the species being peculiar and con- 

 fined each to a single island or small group, we may perhaps 

 consider it as a relic of the indigenous fauna of that more 

 extensive land of which the present islands are the remains. 



The serpentine Amphibia are represented by two species 

 of Caeciliadse. These creatures externally resemble large 

 worms, except that they have a true head with jaws and 

 rudimentary eyes, while internally they have of course a 

 true vertebrate skeleton. They live underground, burrow- 

 ing by means of the ring-like folds of the skin which 

 simulate the jointed segments of a worm's body, and when 

 caught they exude a viscid slime. The young have 

 external gills which are afterwards replaced by true lungs, 

 and this peculiar metamorphosis shows that they belong to 

 the amphibia rather than to the reptiles. The Caecilias 

 are widely but very sparingly distributed through all the 

 tropical regions ; a fact which may, as we have seen, be 

 taken as an indication of the great antiquity of the group, 

 and that it is now verging towards extinction. In the 

 Seychelles Islands there appear to be two species of these 

 singular animals. Hypogeophis rostratits is confined to the 

 islands, while Herpele sqiialostoma is found also in West Africa.^ 



Fresh-water Fishes. — The only other vertebrates in the 

 Seychelles are two fresh-water fishes abounding in the 



^ In the last edition Hypogeophis rostralus was stated to be found also 

 in South America on the authority of specimens in the Paris Museum 

 collected by D'Orbigny. But Dr. Wright informs me that this locality 

 for the species has not been confirmed and is probably erroneous. Hence 

 the discussion upon it is now omitted. 



