that the power of reconstruction from fragments is limited, but not sufficiently 

 so as to justify the epithet " pretension," which has been applied to the claim 

 made. Besides, two other laws remain, which are of great importance to the 

 paleontologist. 



Illustrations of the preceding laws may first be given. If a fragment of 

 an animal be found, which contains a certain type of teeth known as the true 

 selenodont, it is certain, in accordance with the law of uniformity of type, 

 that the first bone of the hind foot of that animal (the astragalus) possessed 

 two pulley-grooved faces, one above and one below, and not one only, as in 

 most animals ; also, that the lower pulley-face was succeeded by two sub- 

 equal toes, and that the lateral toes were either reduced in form or wanting. 

 There is no mechanical relation between the structures of the teeth and foot ; 

 their accordance is simply a fact of type of a selenodont Artiodactyle. 1 Again, 

 if I find a portion of a foot which presents a joint between the first and 

 second rows of bones which form the sole, I am absolutely certain that the 

 animal had the two outer ear-bones external to the skull, forming a part of 

 the lower jaw and the connecting-rod by which the latter is attached to the 

 skull. This is a type-law of the bird and reptile. Again, if I find a part of 

 a foot of the structure just named, where the first row of bones of the sole 

 is united into one mass, and closely embraces the leg-bone without being 

 continuously united, I know that I have an animal with teeth, with a very 

 long hip-bone and a very long series of united vertebrae (or sacrum) resting 

 upon it — in other words, a Dinosaurian. 



The law of uniformity in successional relation is well illustrated by the 

 genus Loxolophodon. The first bone of the foot (astragalus) of this animal 

 exhibits characters intermediate between that of the elephants (Proboscidia) 

 and odd-toed hoofed mammals (example, tapir) ; the remainder of the skeleton 

 does the same ; the neck-vertebras are similar to those of the former, while 

 portions of the skull resemble corresponding ones of the latter. The foot of 

 a dinosaur is intermediate between that of a reptile and that of a bird ; so 

 are the sacrum and pelvis. The sternum of a frog of the family Discoglossidai 

 is intermediate between those of ordinary frogs'and salamanders; so are the 

 vertebras and i*ibs. 



Examples of the limitation of the latter rule are still more numerous. 

 They may be produced from the three cases cited. Thus, in the dinosaur, it 



1 Represented by a Ruminant. 



2 c 



