The Conquest of the Land 



armour - plated type has 

 long ago become extinct, 

 but it is in it, rather than 

 in the modern forms of 

 Amphibia, that we must 

 look for the direct ancestor 

 of man. A fossil of this 

 earlier group is shown on 

 Fig. 90. 



Our next group in the 

 order of Evolution is that 

 of the reptiles, the main 

 differences between which 

 and the Amphibia are of 

 the nature of more complete 

 adaptions to a life on land. 

 The reptiles have in fact com- 

 pleted the conquest of the land 

 which was undertaken by the 

 previous group, and many of 

 them, living as they do in dry 

 and hot deserts, are as inde- 

 pendent of the water as any 

 form of animal life. Thus whereas 

 the amphibian has a thin skin, 

 which is kept moist by the secre- 

 tions of numerous skin glands, the 

 reptile has a body-covering of 

 scales, which form an effective 

 protection against a too rapid 

 loss of moisture. Evidently with 

 the same object, the reptile egg 

 is enclosed in a hard and resistant 

 shell. Correlated with the change 

 in the skin is a much more per- 

 fect development of the lungs, for 



Fig. 89. — The Ceylon Coecilian, IchthyopJiis 



Am 



<^'^=^' 

 ^^o. 



Fig. 90. — Fossil amphibian, BrachiosaiiruSy 

 from the Permian. 



II 



