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FOSSIL REPTILIA OE THE 



chief organic distinction between Hippotherium and Hippos. Every bone, every tooth, 

 present in the eocene and miocene predecessors of modern Horses is retained in them, 

 with slight changes of shape and proportion. The second and fourth metacarpals which 

 bore hoofed digits of moderate size in eocene days, bore them of diminutive size in miocene 

 days ; and now, when such dangling spurious hoofs are gone, their metacarpal and meta- 

 tarsal suspensories still remain, hidden beneath the skin, and ending in a point where, of 

 old, was a well-turned joint. 



It has become as impossible to square the hypothesis of " the peopling of the globe 

 during the long reign of life thereon, by successive and special creations " with the known 

 vital phenomena, as it was impossible to explain the sum of astronomical facts, 

 accumulated in the fourteenth century by the cumbrous machinery of cycles and epicycles, 

 necessitated under the assumption of the globe as the fixed, central, and largest body of 

 the Universe. Biology seems now to be at the Copernican stage; and if the rejection of 

 the incoming of species by primary creative acts should exercise an influence on the pro- 

 gress of that science akin to that of astronomy after the abandonment of the faith in the 

 earth's fixity, Biologists may confidently look for as rapid a progress through acceptance 

 of Nomogeny. 



What, then, may be the meaning of the reduction of bulk in the fore-limbs of certain 

 Dinosaurs ? Does that reduction indicate a step in the conversion of such Reptiles into 

 Birds ? Do we get an explanation of the small fore-limbs by the picture which Professor 

 Phillips vividly presents to us " of the grand and free march on land chiefly, if not solely, 

 on the hind-limbs ?" Or, is the fact of the disproportion of size between the arms and 

 legs in the Megalosaur and Iguanodon susceptible of other than the Oxfordian 

 hypothesis ? 



As a matter of fact, such disproportion is shown by Crocodilian Reptiles still in 

 existence ; whilst extinct Crocodiles of more aquatic habits and marine sphere of life had 

 the fore-limbs as much reduced in size as in any known Dinosaur. 1 Of this Teleosaurian 

 character the physiological explanation which has been advanced is, that the course of 

 such Crocodile through water, due to the action of the long, laterally flattened tail, would 

 be facilitated, or less impeded, by such reduction of size of the fore-limbs, those limbs 

 taking no share in the forward dash of the piscivorous reptile in pursuit of its prey, and 

 if of any use in the water, being limited in natatory evolutions to assist in a change of 

 direction ; the fore-limbs, in fact, being mainly if not wholly required to help in the 

 progress of the amphibious beast upon dry land, or to scratch out the nest in the sand. 

 Actual observation of a swimming Crocodile testifies to the fore-limbs being then laid flat 

 and motionless upon the sides of the chest. All known Dinosaurs have the Crocodilian 

 swimming organ ; the Iguanodon exemplifies the compressed vertically broadened tail in 



1 " Monograph on the Fossil Reptilia of the London Clay," part ii, in the Volume of the Palseonto- 

 graphical Society for 1849, p. 24, t. xi. 



