1871 ] 261 [Cope. 
ber of brown and white bands. The prairie Heterodon, (H. nasicus) pos- 
sesses not only the same tints but the same pattern of coloration, and at a 
short distance cannot be distinguished from it. 
In consequence, as one may justly say, this species is, with the rattle- 
snake, the most common serpent of the plains, as it shares, no doubt, in 
the protection which the armature of the Caudisona gives its possessor. 
This isin accordance with the views of Wallace and Bates. 
A curious case occurred to me in four species of fishes, which I took in 
a small tributary of the Yadkin River, in Roane County, N. C. Among 
several others, there were varieties of the widely distributed species 
Chaenobryttus gillti, Hypsilepis analostanus and- Ptychostomus pidiensis, 
(each representing a different family), which differ from the typical form 
of each in the same manner, viz: in having the back and upper part of 
the sides with longitudinal black lines, produced by a line along the mid- 
dle of each scale. This peculiarity I have not observed in these species 
from any other lecality. Until I had examined them I thought them new 
species. 
The only other species presenting such marking in the Yadkin River, 
is the large perch, the Roccus lineatus. According to the theory of 
natural selection a resemblance to this well armed species might be of ad- 
vantage to the much weaker species in question ; yet the same species 
co-exist in other rivers without presenting the same mimicry. 
It is difficult not to urge the importance of the causes already regarded 
as efficient in the origination of structure, in the present branch of the 
subject also. We are especially disposed to call in use and effort here, 
after noticing how much more distinctly change of color is under the con- 
trol of the animal, than change of shape. It must, however, be borne in 
mind that similar resemblances exist among plants; though, as Prof. 
Dyer shows, a large majority of these cases occur in species of different 
floral regions. Thus in this case, as in those of structure already cited, 
we appeal first to physical laws in the lowest beings, but with the in- 
creasing interference of use, effort aud intelligence, as we rise in the 
scale. Thus it is that in the Vertebrates generally, the mimetic resem- 
blances are found in species of the same region, where only an intelligent 
or emotional agency could be illustrated. If among animals as low as 
butterflies the influence of intelligence be denied, that of admiration for 
the beauty, or fear of the armature, of the predominant species imitated, 
would appear to be sufficient to account for the result. Admiration and 
fear are possessed by animals of very low organization, and with the in- 
stincts of hunger and reproduction, constitute the most intense metaphysi- 
cal conditions of which they are capable. But our knowledge of this 
branch of the subject is less than it ought to be, for animals possess many 
mental attributes for which they get little credit. 
It appears to be impossible to account for the highest illustrations of 
mimetic analogy in any other way, the supposition of Wallace that such 
forms must be spontaneously produced, and then preserved by natural 
