38 ON THE PHYSIOGNOMY OF 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 Avhich 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, wiiich 

 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. 



or THE IIUDIMENTS OF POSTERIOR EXTREMITIES. 



]\Iany 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 t}^e 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 ^'isible, 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 



