172 A Review of the Modern Doctrine of Evolution. (March, 
-“ inexact parallelism, 
” and the relation is presented by forms 
not very nearly phylogenetically related. The more remote the 
Fic. 
4 
Fic. 37. 
Y 
Fic. 3°. 
Fic. 5. 
RANIDÆ. 
phylogenetic lines of two types, the more 
“inexact” will their parallelism be. It was 
once a question whether any parallelism can 
be traced between the members of the five or 
six primary divisions of animals, and in my 
essay on the “ Origin of Genera,” I was 
compelled to state that there was then “no 
evidence of the community of origin of 
these divisions.” Since that time, Haeckel 
has published his “ Gastreea Theory.” This 
is a grand generalization from the facts of 
embryology, which shows the community 
in type of the early stages of all animals, 
and the similarity of the phases which they 
present during a part of ‘their larval life. 
The exceptions to this law which have been 
observed, will probably be explained, as have 
been those which have been urged against 
the law of homologies in anatomy. 
The palzeontology of the Batrachia Anura 
is largely unknown, so we must look else- 
where for proof of the truth of the fourth pro- 
position, viz., that the successional relation 
in embryology corresponds with that shown 
by palzontology to have existed in geo- 
logic time. 
For this purpose I select one of the 
most complete series known to palzontol- 
ogy ; that of the camels or Camelide, whose 
remains are fgund abundantly in various 
parts of our country. The succession of | 
the known genera is seen in the structure of 
the bones of the feet, and of the superior 
incisor and premolar teeth. The metatarsal 
and metacarpal bones are or are not co- 
össified into a cannon bone; the first and 
second superior incisor teeth are present, rudimental or want- 
ing, and the premolars number from four to one. The relations 
