APPENDIX, 
No. I. 
Remarks on the Voluntary Expansion of the Skin of the JVeck in the Cobra de Capello, 
or Hooded Snake of the East Indies. By Patrick Russell, M. D. F. R. S. With a 
Description of the Structure of the Parts which perform that Office. By Everard Home, 
Esq. F. R. S. 
Read before the Royal Society, June 14th, 1804. 
The remarkable expansion of the skin of the neck in the Coluber Naja of Linna:us, or Cobra de Capello 
of the East Indies, and which constitutes a principal character of the species, is produced by an apparatus, 
hitherto, as I believe, very imperfectly described. It is a voluntary action, totally distinct from that infla- 
tion which all serpents when irritated are more or less capable of, and which the Coluber Naja also assumes 
at the same time that it expands its hood. 
In botanical excursions in India, fragments of serpentine skeletons, made by the black ants, were occa- 
sionally met with ; but in such as were supposed to belong to the Coluber Naja, the peculiar disposition and 
structure of the cervical ribs, so different from that in other serpents, had escaped me. 
In other serpents, the ribs from the first vertebra to those of the middle of the trunk gradually increase in 
length; thence they gradually shorten or decline to near the end of the tail, where they disappear or are 
transformed into short eminences ; but in the Coluber Naja, the cervical ribs gradually lengthen to the 
tenth or eleventh, after which they successively shorten to the twentieth. The ribs, again increasing in 
length, are at the middle of the trunk, nearly as long as the middle cervical ribs, and then declining, as 
usual in other serpents, disappear on the tail. 
So obvious a peculiarity in the skeleton of the Cobra de Capello, having escaped my notice in India, and 
finding myself unable to account for the expansion of its hood, which is commonly, in that country, con- 
ceived to be connected with inspiration, I brought with me, on my return to England, several subjects for 
dissection, in order to have the matter properly ascertained ; my friend Mr. Home readily undertook the 
task, and the subjoined result of his investigation will, I have no doubt, prove satisfactory. 
I have on another occasion asserted as a fact, that the neck of the Cobra de Capello, in a quiescent state, 
shews no external protuberance whatever;* and it is clearly accounted for in the following description, 
from the ribs, when depressed, lying upon the spine over one another. 
MR. HOME’S DESCRIPTION. 
The mechanism by which the Cobra de Capello, when irritated and ready to seize its prey, expands the 
skin of the neck, giving it the appearance from which the snake takes its name, consists entirely of muscles, 
acting upon the ribs and external skin of the animal. 
From the rounded form of the hood, the skin has the appearance of being inflated ; but the most careful 
examination did not discover any communication between the trachea or the lungs and the cellular mem- 
brane under the skin. 
In this snake, the ribs nearest the head, to the number of twenty on each side, have a different shape from 
the rest ; instead of bending equally with the other ribs towards the belly, they go out in a lateral direction, 
having only a slight curvature, and when depressed, lie upon the side of the spine on one another. 
* Continuation of an Account of Indian Serpents, page 3. 
