132 THE EVOLUTION OF MAN. 



groups. This remarkable transformation is, in other respects 

 also, of general interest, as throwing a flood of light upon the 

 Phylogeny of the Tail-less Apes and of Man. Man's ances- 

 tors were also long-tailed gill-breathing animals, resembling 

 Gilled Batrachians, as is irrefutably demonstrated by the 

 tail and the gill arches in the human embryo. 



During the Palaeozoic Epoch, and probably in the Car- 

 boniferous Period, there is no doubt that the Amphibian 

 class embraced a series of forms which must be regarded as 

 direct ancestors of Mammals, and so of Man. On grounds 

 derived from Comparative Anatomy and Ontogeny, we must 

 not, however, look for these Amphibian ancestors of ours 

 as might perhaps be supposed among the Tail-less Frog 

 Batrachians, but only among the lower Tailed Amphibians. 

 We can with certainty point to at least two extinct Batra- 

 chian forms as direct ancestors of Man, as the thirteenth 

 and fourteenth stages in our pedigree. The thirteenth 

 ancestral form must have been closely allied to the Double- 

 breathers (Dipneusta), must, like these, have possessed per- 

 manent gills, but must have been already characterized by 

 having five digits on each foot ; and were they still living we 

 should place them in the group of Gilled Batrachians, with 

 the Proteus and the Axolotl (Plate XIII. Fig. 1). The 

 fourteenth ancestral form, on the other hand, must indeed 

 have retained the long tail, but must have lost the gills, and 

 hence the nearest allied forms among extant Tailed Batra- 

 chians would be the Water-Newts and Salamanders 

 (Plate XIII. Fig. 2). Indeed, in the year 1725 the fossil 

 skeleton of one of these extinct Salamanders (closely allied 

 to the present giant Salamander of Japan) was described 

 by the Swiss naturalist, Scheuchzer, as the skeleton of 



