CHAP. XIX THE MADAGASCAR GROUP 433 



when we consider the habits of life of these animals and 

 the extreme slowness with which it is likely they can 

 migrate into new areas, we can hardly arrive at any other 

 conclusion than that this species once had an almost 

 Avorld-wide range, and that in the process of dying out it 

 has been left stranded, as it were, in these three remote 

 portions of the globe. The extreme stability and long 

 persistence of specific form which this implies is extra- 

 ordinary, but not unprecedented, among the lower verte- 

 brates. The crocodiles of the Eocene period differ but 

 slightly from those of the present day, while a small fresh- 

 water turtle from the Pliocene deposits of the Siwalik 

 Hills is absolutely identical with a still living Indian 

 species, Emys tectus. The mud-fish of Australia, Corttochcs 

 forsteri is a very ancient type, and may well have remained 

 specifically unchanged since early Tertiary times. It is 

 not, therefore, incredible that this Seychelles Csecilia may 

 be the oldest land vertebrate now living on the globe ; 

 dating back to the earl}^ part of the Tertiary period, when 

 the warm climate of the northern hemisphere in high 

 latitudes and the union of the Asiatic and American con- 

 tinents allowed of the migration of such types over the 

 whole northern hemisphere, from which they subsequently 

 passed into the southern hemisphere, maintaining them- 

 selves only in certain limited areas, Avhere the physical 

 conditions were especially favourable, or where they were 

 saved from the attacks of enemies or the competition of 

 higher forms. 



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

 Seychelles are two fresh-water fishes abounding in the 

 streams and rivulets. One, Haplochilus i^layfairii is 

 peculiar to the islands, but there are allied species in 

 Madagascar. It is a pretty little fish about four inches 

 long, of an olive colour, with rows of red spots, and is very 

 abundant in some of the mountain streams. The fishes of 

 this genus, as I am informed by Dr. Gilnther, often inhabit 

 both sea and fresh water, so that their migration from 



in the Paris Museum were brought by D'Orbigny from S. America. Dr. 

 AVright's specimens from the Seychelles liave, as he informs me, been 

 determined to be the same species by Dr. Peters of Berlin. 



F F 



