384 FISHES OF WESTERN SOUTH AMERICA 
show about 16-17 spinous rays in the anal fin, where our specimens have but 12 
(at most 13). His description does not allude to the ashen markings seen in 
mimophyllus, nor do they appear in the photograph from life. 
Mr. Innes’s illustrations show a specimen with mouth distended, clarifying 
better than our fig. 2 (1921 paper) the significance of the unusual visceral skeleton. 
It is of interest to note here that the Agassiz in their book, A Journey in Brazil, 
pages 161 and 238, make allusion to certain fishes of the Amazon which are mimics 
of dead leaves. These they assign to a family Folhidae, a Portuguese word latinized. 
The derivation of the name is quite appropriate, but I have found no evidence 
that it ever attained proper standing. 
THE PRESENT STATUS OF THE THEORY OF MIMICRY 
McAtee and others have recently held up for much adverse criticism the 
entire matter of mimicry in animals. The ground for their antagonism seems to be 
the fact that animals possessing it do not appear to enjoy a measurably higher 
survival rate in Nature than others. We are constrained, they say, to reject the 
doctrine entirely. If other animals not so protected live as long on the average, 
the species has not been subjected to the operation of Natural Selection, and no 
mechanism other than random selection has brought about the infringement of 
copyright. 
So far as it reaches, the argument mentioned is very convincing, and doubtless 
completely satisfying to many good zoologists. However, should the term mimicry 
fall into complete disuse and be forgotten, we still have a phenomenon needing a 
name, one of the most vivid and interesting in all the realm of Nature. Perhaps 
a better name will be forthcoming, but likely not if we are looking for a term which 
will explain the phenomenon to the general satisfaction of the zoological world. 
We do have a well-known phenomenon. Certain animal forms do show a 
clear-cut resemblance to other objects in their environment. We do have a mas- 
querading act whether we like it or not, and whether we can explain it or not. This 
masquerade goes on in the immediate vicinity of the object which is imitated, and 
not at remote, unrelated points. Perhaps the greatest objection to the word 
mimicry is the fact that it seems to imply psychic factors, that the imitator exercises 
a voluntary control of its own evolution. We are unable to understand the inter- 
mediate steps by which the mimic has arrived at perfection, except as a long line 
of consciously-directed mutations or gradations. 
This phylogeny cannot be shown to have had psychic elements; it has not been 
demonstrated that mimicry has effective selection value; its processes are not known, 
nor are the respective cases of mimicry known to have arisen in the same manner. 
My thesis here is to defend the use of the name until its true name shall have been 
revealed. 
At this juncture it would appear that what we need is a new definition rather 
than a new provisional name, since no new explanation is available. 
We might raise some inquiry as to the occurrence in Nature of intermediate 
stages in the evolution of this at least quasi-mimicry. For such mimicry-in-the- 
