260 



THE DOCTRINE OF DESCENT. 



physiological ascent, linked with various morphological 

 transformations, which may similarly be shown between 

 the ancient and modern specimens of the Labyrintho- 

 donts. The Batrachians, indeed, rise higher in develop- 

 ment than the Ccecilia ; but, as the friend above men- 

 tioned informs me, they more nearly approach the 

 Myxine in the construction of the internal gills of their 

 larva. We shall obtain a general view of the reptiles 

 by means of the appended diagram, in which we shall 

 avoid any minute systematic designations. 



