52 CEREBRAL DEVELOPMENT 



my specimens fail to show them. The general arrangement 

 was of much elegance, — an elegance, however, which,- in the 

 accompanying restorations, the dislocation of the free plates, 

 drawn apart to indicate their detached character, somewhat 

 tends to obscure. But the position of the eyes must have 

 imparted to the animal a sinister, reptile-like aspect. Tlie 

 profile (fig. 15), the result, not of a chance-di-awn outline, arbi- 



Fi^. 15. 



HEAD OF OSTEOLEPIS, SEEN IN PBOFILE. 



trarily filled up, but produced by the careful arrangement in 

 their proper places of actually existing plate, serves to show 

 how perfectly the dermoskeletal parts of the creature were 

 developed. Some of the animals with which we are best 

 acquainted, if represented by but their cuticular skeletons, 

 would appear simply as sets of hoofs and horns : even the 

 tortoise or pengolin would present about the head and limbs 

 their gaps and missing portions. But the dermoskeleton of 

 the Osteolepis, composed of solid bone, and burnished with 

 enamel, exhibited the outline of the fish entire, and, with the 

 exception of the eye, the filling up of all its external parts. 

 Presenting outside, in its original state, no fragment of skin 

 or membrane, and with even its most flexible organs sheathed 

 in enamelled bone, the Osteolepis must have very much re- 

 sembled a fish carved in ivory; and, though so efiectually 

 covered, it would have appeared, from the circumstance, that 



