M P ' '
II
5 0 A P P E N D I X No. II.
I have, in the course of the last three years, received two Colubers from Java; and, by favour of Dr.
CLAHK, two from Martinico; all four venomous, and distinguished by lateral orifices. In the month of
January, !803, Dr. GARTUSIIOHE presented me with a specimen of the yellow snake of Martinico in excellent
preservation.
Six subjects, distinguished by these lateral orifices now in my possession, offering a fair opportunity to determine
a curious circumstance in comparative anatomy, the specimens were submitted to my friend Mr.
HOME, of whose assistance I had more than once availed myself in similar investigations. My request was
once more attended to; and the stibjoined Description and Remarks were received in return.
Among the specimens submitted to MI'. HOME, was one of the Bodroo Pani, in the description of which,
lately published,* 1 have misrepresented the orifices now in question as the nostrils, having intirely overlooked
the real nostrils.
AMrilc the anatomical disquisitions were going on, inspection was made into some of the numerous collections
of serpents ])reserved in the Museums in London. In the British Museum I was sheu-n, e.vclusive of the
Rattle-snake and the Fer-de-lance, four or five Colubers,t with lateral orifices; in the LEVEKIAN Museum I
found two or three; in theHoNTEElAi« Museum,two Colubers,i: and three Boa; ;§ and in that ofMr. HE/IVISIUE,
one Coluber.ll
The total found in the Museums above-mentioned, (exclusive of the Rattle-snake,) were (en or eleven
Colubers, and three BOK ; which, added to live Colubei-s in my own possession, amount to eighteen or nineteen
subjects furnished with lateral orifices.
It appears on the whole, that the lateral orifices have hitherto been found only in venomous serpents.
That (exclusive of the Rattle-snake), they have been found in fifteen or sixteen species of Colubers, and in
three of the Genus Boa.
That they have not as yet been discovered in any of the Genus Anguis.
Mr. H03IE'S investigations have clearly established that these lateral orifices in serpents, and the bags to
which ihey lead, have no communication with the organ of hearing. Another fact ascertained by him is,
that serpents distinguished by lateral orifices, h a v e a cavity situated between the bag and the eye, which, so
far as I know, has not been observed before.
MR. HOME'S DESCRIPTION AND REMARKS.
THE orifices situated between tlie eye and the nostril in the Rattle-snake, and in some species of Coluber,
do not lead to the nostril or to the ear, but to a distinct bag of a rounded form; there is a hollow of the
same shape surrounded by bone, and adapted to receive it. Dr. TYSON'S description of the Rattle-snake is
tolerably accurate : he says, " between the nostrils and the eyes, but somewhat lower, were two orifices which
" I took for the ears, but after, I found they only led into a bone that had a pretty large cavity, but no
" perforation."^
The cavity which Dr. TYSON describes to be in the lione, is a cup, formed liy the bones of the skull and
those of the upper ja%v; it is in shape not unlike the orbit, and is formed in a similar manner.
These bags bear a relative proportion lo the size of (he snake ; they are lined, as also the eyelids, with a
cuticle which forms the transparent cornea, making a part of the outer cuticle, and is shed with it ; and, when
examined after the snake has cast it off, their shape is more perfectly seen than under any other circumstances.
In the annexed figures one of these bags is represented in different views ; all of them of the natural size,
both in the Fer-de-lance or yellow snake of Martinico, and in the detached culicle of Ihe Rattle-snake. The
appearance in the Bodroo I'am is exactly the same ; but, as the bag in that snake is of a smaller size, it was
considered unnecessary to give a representation of it.
In the deer and antelope there are bags, in the same relative situation repecting the eye and the nose,
IX. t All I believe Nondeicripli.
A P P E N D I X No. II. 51
resting upon the skull ; there is also a cavity in the bone adapted to receive them. The bags vary in size in
the different species of these genera. The French naturalists have given the name of larmiers lo these
bags, conceiving them to be receptacles for the tears, of which the thinner parts evaporating, a substance
remains called larmes de cerf,
I requested my friend Mr, ANDEE to examine these bags in the common buck, and to observe their relat
i v e position to the puncta lachiymalia; his situation in the Earl of EGKEMONT'S family at Petworth affording
him every opportunity for doing it. I-Ie informs me that the bags are lined with a cuticle similar to
that of the meatus audilorius externus in the human ear ; their internal surface is smooth, free from hair,
and without any appearance of glandular structure. From the inner angle of the eye to this bag, there is a
kind of gutter in the skin, of a darker colour than the rest of the skin in light coloured animals, and the hairs
are shorter than on the rest of the body: the substance contained in the bags resembled that found in the
ears.
The lathrynial gland in the deer, he says, is very large, and the puncta so much so, as lo admit the
rounded end of a common probe. There is no lachrymal sac ; the tubes from the puncta unite and pass
through a small opening in the bone to the nose.
The following account of these bags, in the Antelope of Sumatra, was transmitted (o me in the year 1799,,
b y Mr. BELE. " The external orifice is of the size of a crow quill ; it leads into a bag not larger than a
" small marble, which is lined with a cuticle with hair. From this bag there is a secretion of a limpid fluid,
" which keeps oozing down the nose." This gentleman, unfortunately for Natural History, died at Sumatra
soon after the date of his letter.
In the HONTEMAN Museum, intrusted by Government to the care of the College of Surgeons, there are
several specimens of these bags from the Egyptian Antelope, with annulated horns, and also from some
other species ; these are preserved so as to shew the internal cavity of the bag, and the structure of the
gland immediately behind it. In these specimens the glandular part is one-fourth of an hich in thickness;
from the centre of this gland, an excretoiy duct opens into the bag immediately opposite to the external
orifice. The bag itself is lined with a cuticle, and thinly set with strong hairs.
The facts now produced are sufficient to prove that these bags have a secretion of their own, the quantity
of which varies according to the climate-and other circumstances; and there is no reason for thinking that
the teai-s ever pass into them, the passage into the nose being unusually free, and the orifices in the bags in
many species unfavourably situated for the reception of the tears.
We are at present unacquainted with the use to which the fluid secreted in these bags is applied.
A s amphibious animals, in general, have no glands to supply the skin with moisture from within, but
receive it by coming in contact with moist substances, it is possible the bags in the snake may be supplied in
that manner, and the more so, as the cuticular lining appears perfect.
Another peculiarity is remarkable in snakes furnished with the bags described above, namely, an oval
c a v i t y situated between the bag and the eye, the opening into which is within the inner angle of the eyelid,
and directed towards the cornea. In this opening there are two rows of projections which appear to form
an orifice capable of dilatation and contraction. From the situation of these oval cavities, they must be considered
as reservoirs for a fluid, which is occasionally to be spread over the cornea; and they may be filled
b y the falling of the dew, or the moisture shaken off from the grass through which the snake passes.
This apparatus in the suake lias that position which is best adapted to pour out the fluid upon the cornea,
when the head of the snake is erect.
Dr. TYSON had superficially observed the apparatus which has been described, and considered it as a
inembrana nictitans. He says, " inwards it seemed to have a membrana nictitans, which removes any dust
" that might adhere to fhe eye."*
« PUil. Trans, vol. p. 27.