214 THE POPULAR SCIENCE MONTHLY. 



and many varieties of ruminants. These latter have their definite 

 characteristics, and the former have their distinguishing peculiarities. 

 But there is nothing that fills up the gap between the ruminants and 

 the pig tribe. The two are distinct. So also is this the case between 

 the groups of another class reptiles. We have crocodiles, lizards, 

 snakes, and tortoises, and yet there is nothing no connecting link 

 between the crocodile and lizard, or between the lizard and snake, or 

 between the snake and the crocodile, or between any two of these 

 groups. They are separated by absolute breaks. If, then, it could be 

 shown that this state of things was from the beginning had always 

 existed it would be fatal to the doctrine of evolution. If the inter- 

 mediate gradations which the doctrine of evolution postulates must 

 have existed between these groups if they are not to be found any- 

 where in the records of the past history of the globe all that is so 

 far a strong and weighty argument against evolution ; while, on the 

 other hand, if such intermediate forms are to be found, that is so 

 much to the good of evolution, although, for the reason which I will 

 put before you by-and-by, we must be cautious in assiaming such facts 

 as proofs of the theory. 



It is a very remarkable fact that, from the commencement of the 

 serious study of paleontology, from the time in fact when Cuvier 

 made his brilliant researches upon the fossil remains of animals found 

 in the quarries of Montmartre, Paleontology has shown what she was 

 going to do in this matter, and what kind of evidence it lay in her 

 power to produce. 



I said just now that at the present day the group of pig-like ani- 

 mals and the group of ruminants are entirely distinct ; but one of the 

 first of Cuvier's discoveries was an animal which he called the Ano- 

 plotherium, and which he showed to be, in a great many important 

 respects, intermediate in its character between the pigs on the one 

 hand and the ruminants on the other; that, in fact, research into the 

 history of the past did so far and to the extent which Cuvier indi- 

 cated tend to fill up the breach between the group of ruminants and 

 the group of pigs. All subsequent research has also tended in this 

 direction ; and at the present day the investigations of such men as 

 Rutimeyer and Gaudry have tended to fill up and connect, more and 

 more, the gaps in our existing series of mammals. But I think it may 

 have an especial interest if instead of dealing with these cases, which 

 would require a great deal of tedious osteological detail I take 

 the case of birds and reptiles which groups, at the present day, are 

 so clearly distinguished from one another that there are perhaps no 

 classes of animals which in popular apprehension are more completely 

 separated. Birds, as you are aware, are covered with feathers ; they 

 are provided with wings ; they are specially and peculiarly modified 

 as to their anterior extremities; and they walk perpendicularly upon 

 two legs; and those limbs, when they are considered anatomically, 



