181 
[Garman. 
The result is so directly in the way of the actual development seen 
in the copperhead that one should not be at all surprised to find an 
occasional specimen of this serpent on which the cap still clung to 
the button. 
While this might furnish the creature with a rattle, the approach 
to which is so very near already, it would do so without traversing 
the entire distance between it and its nearest allies, the “Massasau- 
gas” and the “Ground Rattlers” of the genus Sistrurus. Yet to 
bridge over the gap between them it will be necessary to call in the 
assistance of nothing but what is naturally induced by change of 
habit. 
Immediately upon the establishment of the rattle, the influence 
of its presence would begin to assert itself. The acquisition of the 
organ would be as likely to involve changes in structure, as a removal 
from a damp to a dry and rocky locality to induce those of habits 
and consequently of anatomy. The tail of the copperhead is slender 
and very flexible towards the end ; a condition favoring the present 
method of making sound. A cap clinging to the button would in- 
terfere, and, further, in the more soft and tender condition of the 
ever sensitive skin of the extremity, at the time of casting the 
slough, would in all probability inflict punishment if struck against 
objects offering resistance. Inconvenience and distress from at- 
tempts to practise the old method and, afterward, discovery of abil- 
ity to accomplish the same result in a new one, would be powerful 
inducements to change. The motions when rattling in the air with- 
out percussion are much like those made by the snake when the tail 
is pinched or hurt, a possible effect of an outgrown cap. Rigidity 
rather than flexibility is demanded in the tail when vibrated in short, 
quick strokes without contact with anything. Loss of flexibility 
would follow such usage and the slenderness would gradually disap- 
pear, because of the development of muscles formerly neglected, 
but newly called into use, and with it of enlargemen t of the vertebrae 
to which the muscles are attached. The forward muscular strain, 
simultaneously applied, above, below, and at the sides of the col- 
umn, during exercise of the muscles in crepitation, would tend to 
shorten the tail, and, with increase in size of the cap, to consolida- 
tion of the posterior vertebrae. 
In short, the course outlined here would result in transferring a 
species from one genus to another : starting as a copperhead, An- 
ctstrodon , the animal would finally appear as a ground rattler, Sis- 
