1877.]| Provisional Hypothesis of Saltatory Evolution. 135 
doubt that the masters in modern biological thought have a 
ready answer to all or most of the questions which naturally 
arise in a thinking mind while considering the existence of scav- 
engers among animals. Is not the subject worthy of their 
further attention, and may we not have the pleasure of reading 
their views in the Naturalist ? 
ON A PROVISIONAL HYPOTHESIS OF SALTATORY 
EVOLUTION. 
BY W. H. DALL. 
is has long been brought forward, as against the Evolutionary 
Theory, that there were missing links in the chain of devel- 
opment which could not fairly be charged to the account of de- 
ficiencies in the palzontological record. This is the chief weapon 
of all opponents to the doctrines so generally received by mod- 
ern naturalists. The number of instances in which the objection 
is well founded has been much exaggerated, but that there are 
cases of the kind will not, I think, be denied by any impartial 
student, though some imprudent partisans of the new faith have 
rather scoffed at the idea. 
Having confidence that evolution when fully understood in 
all its modes will prove amply sufficient to account for all phases 
of organization, and realizing that leaps, gaps, saltations, or 
whatever they may be called, do occur, I have for some years 
made this branch of the subject a matter of reflection in the 
hope of arriving at some clew to the mode. 
_ Ihave had my attention more especially called to the matter 
in studying a phase of the kind of evolution I have here termed 
saltatory, which is especially referred to in Cope’s paper on the 
: rigin of Genera, where, if I recollect rightly, it finds expression 
m the paradox that “the same species may belong to two dif- 
ferent genera.” 1 That is, more explicitly, that species which are 
abundantly proved to be distinct from each other by generic char- 
acteristics may be, so far as their specific characters are concerned, 
hot distinguishable from one another. Such cases are mentioned 
by Cope in the paper alluded to, and there are other well-known 
instances of the paradox among birds, Crustacea, and Brachiopoda. 
Q.) As an illustration of how the apparent leaps, which 
. Not having seen Professor Cope’s paper since about the time of its publication, 
and a copy not being accessible to me at this time, I may not have quoted the exact 
Words, but the idea is the same 
