SURVEY OF VERTEBRATES 



131 



tenaciously conserved and appears again and again in 'higher' 

 phyla. So there is a trace of structural and physiological continuity 

 woven in the picture of animal life that is interpreted as evidence 





Mm 





=%'- 



IMmm 



4/,/ ,/jJk,i». v V/ 



C D 



Fig. 93. — Primates. A, Dwarf Lemur, Microcebus smilhii; B, Spider 

 Monkey, Ateles ater; C, Baboon, Papio leucophoeus; D, Gibbon, Hylobates 

 lar. (From Newman, after Beddard and Lydekker.) 



of descent with change, or evolution. The appreciation of this unity 

 in diversity will contribute toward the proper perspective for a 

 more detailed consideration of the Vertebrate body and a pres- 

 entation of certain general biological principles. 



