234 The American Naturalist. [March, 
In the embryos of some birds the rudiments of teeth are dis- 
tinctly traceable@yet in no class of birds extant do the teeth pass 
beyond this rudimentary stage. How can these rudimentary 
organs be explained by believers in special creations? Surely 
not, as is usually explained, “in order to complete the scheme of 
nature” or “for the sake of symmetry,” for if these be the rea- 
sons, why do not the rudimentary teeth appear in the embryos of 
all birds, of turtles, and of some ant-eaters, where they are not 
present at any age? On the other hand, how clear the question 
becomes in the light of evolution by natural selection! As Dar- 
win has so aptly put it; “ The unity of type is explained by unity 
of descent.” 
Nor can rudimentary organs be explained by assuming them of 
some use to the animals. On the contrary there are some of 
positive harm to the possessor. Confined to the teeth as we are 
by the present discussion, we can still find an instance here, and 
in no less an animal than man himself. There are in the upper 
jaw two small premaxillary bones which in the lower animals 
remain distinct and separate throughout life, but in man early be- 
come fused with the larger maxillary bones. It is from this pre- 
maxillary bone that the upper incisors spring. Now in a certain 
proportion of cases these premaxillary bones do not become 
et in man, oe remain separated. This is the condition in 
tl i tion known as hare-lip, from its resemblance 
to the Foondition found normally in the hare family. Now does 
it not seem reasonable to suppose that, if man were a special 
creation, he would have been created without a premaxillary 
bone? In view of this defect, while man does possess a 
marvelously complete apparatus, it is thus far not a perfect 
mouth. 
Dr. Bonwill makes the claim that, since the jaw of man is an 
equilateral triangle, it is the most perfect of mouths. The perfec- 
tion here must be comparative rather than absolute. It is no 
more perfect in its way than the jaw and teeth of the serpent, 
the well developed canines of the Carnivora, and the grinding 
molars and lateral motion of the jaw of the Herbivora, are in 
their way. Each is no more perfect for its use than the others 


