l6 GEOGRAPHICAL DISTRIBUTION [CHAP. VII 



Letter 391 with enormous fresh-water lakes, from the Permian period to 

 the present day. If I remember right, he believes in a former 

 connection with S. Africa. 



I am sure that I read, some twenty to thirty years ago 

 in a French journal, an account of teeth of Mastodon 1 found 

 in Timor ; but the statement may have been an error. 



With respect to what you say about the colonising of 

 New Zealand, I somewhere have an account of a frog frozen 

 in the ice of a Swiss glacier, and which revived when thawed. 

 I may add that there is an Indian toad which can resist 

 salt-water and haunts the seaside. Nothing ever astonished 

 me more than the case of the Galaxias ; 2 but it does not 

 seem known whether it may not be a migratory fish like 

 the salmon. 



Letter 392 To A. R. Wallace. 



Down, June 25th, 1876. 



I have been able to read rather more quickly of late, and 

 have finished your book. I have not much to say. Your 

 careful account of the temperate parts of South America 

 interested me much, and all the more from knowing some- 

 thing of the country. I like also much the general remarks 

 towards the end of the volume on the land molluscs. Now 

 for a few criticisms. 



P. I22. 3 I am surprised at your saying that "during the 

 whole Tertiary period North America was zoologically far 

 more strongly contrasted with South America than it is now." 

 But we know hardly anything of the latter except during the 

 Pliocene period ; and then the mastodon, horse, several great 

 edentata, etc., etc., were common to the north and south. If 



continent. Since the publication of Blanford's paper, much literature has 

 appeared dealing with the evidence furnished by fossil plants, etc., in 

 favour of the existence of a vast southern continent. 



1 In a letter to Falconer (Letter 155), Jan. 5th, 1863, Darwin refers 

 to the supposed occurrence of Mastodon as having been " smashed " by 

 Falconer. 



2 The only genus of the Galaxidae, a family of fresh-water fishes 

 occurring in New Zealand, Tasmania, and Terra del Fuego, ranging 

 north as far as Queensland and Chile (Wallace's Geogr. Distrib., II., 

 p. 448). 



3 The pages refer to Vol. II. of Wallace's Geographical Distribution. 



