CHAPTER V.. Proofs From Homologies of the Vertebrate Skeleton.

PROOFS FROM HOMOLOGIES OF THE VERTEBRATE SKELETON.

Common general plan--In several respects--Strongly suggestive of common origin--Details of structure demonstrative of the same 111

Special homology of vertebrate limbs 113

Fore-limbs--Comparison of fore-limbs of mammals, birds, reptiles, and fishes, part for part--Gradual changes in collar-bone and coracoid--In position of elbow--In bones of forearm--In position of wrist--In the tread--The term manus--Number of toes--Modifications for flight in various animals--For swimming in whales and fishes 113

Hind-limbs--Comparison of hind-limbs of several mammals-- Position of knee--Of heel--Plantigrade and digitigrade --Degrees of the latter--Number of toes--General law in regard to number of similar parts--Order of toe-dropping in artiodactyles--In perissodactyles 121

Genesis of the horse--Changes in foot-structure--Same true of other parts of skeleton--Only natural explanation is derivation--Nature compared with man in mode of working-- Angels--Griffins--Centaurs--Muscular and nervous systems --Visceral organs 126