The Theory of Evolution 51 
hippus ina series, for these names stand not for single species, 
but for groups containing no less than six species under 
Protohippus, fourteen under Equus, twelve under Mesohippus, 
and twenty under Hipparion. Fleischmann concludes: “The 
descent of the horses has not been made out with the precision 
of an accurate proof, and it will require a great deal of work 
before we get an exact and thorough knowledge of the fossil 
forms. What a striking contrast is found on examination be- 
tween the actual facts and the crude hopes of the apostles 
of the descent theory! .. .” 
In so far as this criticism of Fleischmann’s applies to the 
difficulties of determining the past history of the horse, it may 
be granted that he has scored a point against those who have 
pretended that the evidence is simple and conclusive; but we 
should not fail to remember that this difficulty has been felt 
by paleontologists themselves, who have been the first to call 
attention to the complexity of the problem, and to the diffi- 
culties of finding out the actual ancestors of the living 
representative of the series. And while we may admit that 
the early enthusiasts exaggerated, unintentionally, the im- 
portance of the few forms known to them, and went too far 
in supposing that they: had found the actual series of ances- 
tors of living horses, yet we need not let this blind us to the 
importance of the facts themselves.. Despite the fact that it 
may be difficult and, perhaps, in most cases, impossible, to 
arrange the fossil forms in their relations to one another and 
to living forms, yet on an unprejudiced view it will be clear, 
I think, that so far as the evidence goes it is in full harmony 
with the theory of descent. This is especially evident if we 
turn our attention to a part of the subject that is almost 
entirely ignored by Fleischmann, and yet is of fundamental 
importance in judging of the result. The series of forms 
beginning with the five-toed horses and ending with those 
having a single toe has not been brought together haphazard, 
as Fleischmann’s comparison might lead one to suppose, but 
