MAMMALIA. 335 



Prior to the time of Cuvier but little progress had been 

 made in the interpretation of snch fragmentary remains. The 

 striking success which attended the application of the great 

 comparative anatomist's science to this previously neglected 

 field of study, was referred by Cuvier to principles in the 

 organization of animal bodies, which he termed the " Correla- 

 tion of Forms and Structures," and the " Subordination of 

 Organs" — principles which his clear- thinking biographer, M. 

 Flourens,* in common with most contemporary philosophers, 

 has regarded as the most effective and successful instrument 

 in the restoration of extinct animals. They will be exempli- 

 fied in the course of the present section of this work. 



A terminal phalanx modified to fit a hoof may give, as 

 Cuvier declared, the modifications of all the bones of the fore 

 limb that relate to the absence of a rotation of the fore leg, 

 and all the modifications of the jaw and skull that relate to 

 the mastication of food by broad-crowned complex molars. 



But there are certain associated structures for the coinci- 

 dence of wliich the physiological law is unknown. " I doubt," 

 writes Cuvier, " whether I should have ever divined, if obser- 

 vation had not taught it me, that the ruminant hoofed beasts 

 should all have the cloven foot, and be the only beasts with 

 horns on the frontal bone."t We know as little why horns 

 should be in one or two pairs on the frontal bone of those 

 Ungulates only which have hoofs in one or two pairs ; whilst 

 in the horned Ungulates with three hoofs there should be 

 either one horn, or two horns placed one behind the other in 

 the middle line of the skull ; or why the Ungulates with one 

 or three hoofs on the hind foot should have three trochanters 

 on the femur, whilst those with two or four hoofs on the hind 

 foot should have only two trochanters. 



* Eloge Historique et l'Analyse Baisonnee des Travaux de G. Cuvier, 12mo, 

 Paris, 1841, p. 42. 



f " Recherckes sur les Ossemens Fossiles," 8vo, ed. 1834, tom. i., p. 184. 



