38 
ON THE PHYSIOGNOMY OP SERPENTS. 
passes below the salivary glands, to be attached, as a broad 
riband, on the lower jaw ; the fibres which are prolonged 
over the poison gland, and which serve to compress it in 
the act of biting, proceed also from this muscle. The 
muscle which stretches from the upper surface of the tym- 
panites has been compared to the Digastric. The muscle 
passing from the articulation of the lower jaw to the ex- 
ternal pterygoids has got its name from this last bone ; in 
venomous snakes it sends off two tendons, one destined for 
the maxillary bone, the other for the capsule of the fangs. 
Besides the muscles just described, two others exist, which 
take their origin near the articulation of the lower jaw : 
1st, The internal pterygoids; and, 2d, The muscle which 
is fixed to the base of the occiput. A third long muscle 
unites the internal pterygoid to the sphenoid bone, to which 
it is often attached by two heads. Lastly, there exists a 
small muscle between the sphenoid and the palatal bones. 
OP THE RUDIMENTS OP POSTERIOR EXTREMITIES. 
Many serpents have a little hook or spur at each side 
of the anus, half concealed by the scales, which has been 
long since recognised ; but we owe to Professor Mayer 
of Bonn, the first accurate account of it. This philosopher 
has demonstrated, that these organs should be considered 
as vestiges of Posterior Extremities, In the order of 
Ophidians, these bones have hitherto been detected only 
in the true Tortrix, the Boas, and the Pythons ; all other 
serpents, according to my observations, are wholly de- 
prived of them. These organs are strongly developed in 
the Boas ; and the size of those animals being favourable 
to the examination of parts so delicate, the type of the 
description of these organs is taken from this genus. 
These vestiges of inferior extremities consist, on each side, 
of an assemblage of three principal bones, and two small 
accessory pieces, attached to the articulation of a tibia and 
a tarsus. The terminal bone, the only one that is exter- 
nally visible, has the form of a crooked nail, covered with 
a hard scaly skin. We discover, by means of a longitu- 
dinal incision in the muscles at the side of the anus, that 
