404 



ISLAND LIFE. 



[part II. 



true lungs, and this peculiar metamorphosis shows that they 

 belong to the amphibia rather than to the reptiles. The Csecilias 

 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 two 

 species have been found, named respectively Ccecilia oxyura 

 and C. rostrata. ■ The former also inhabits the Malabar coast of 

 India, while the latter has been found in West Africa and also 

 South America.^ This is certainly one of the most remark- 

 able cases of the wide and discontinuous distribution of a species 

 known ; and when we consider the habits of life of these animals 

 and the extreme slowness with which it is likely they can mi- 

 grate into new areas, we can hardly arrive at any other conclu- 

 sion than that this species once had an almost world-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 ex- 

 treme stability and long persistence of specific form which this 

 implies is extraordinary, but not unprecedented, among the lower 

 vertebrates. The crocodiles of the Eocene period differ but 

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

 turtle from the Miocene deposits of the Siwalik Hills is abso- 

 lutely identical with a still living Indian species, Emys tectus. 

 The mud-fish of Australia, Ceratodus forsteri is a very ancient 

 type, and may well have remained specifically unchanged since 

 early Tertiary times. It is not, therefore, incredible that the 

 Seychelles Csecilia may be the oldest land vertebrate now living 

 on the globe ; dating back to the early part of the Tertiary period, 

 when the warm climate of the northern hemisphere in high 

 latitudes and the union of the Asiatic and American continents 

 allowed of the migration of such types over the whole northern 

 hemisphere, from which they subsequently passed into the 

 southern hemisphere, maintaining themselves only in certain 



1 Specimens are recorded from West Africa in the Proceedings of the 

 Academy of Natural Science, Philadelphia, 1857, p. 72, while specimens in 

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

 Wright's specimens from the Seychelles have, as he informs me, been 

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



