OF THE GLANDS. 45 



extremity of the maxillary bone, several teeth longer than 

 tlie rest ; the teeth of the Dryiophis and Psammophis are 

 very unequal, and we find several very long at the middle 

 of the jaws and at the posterior part of the maxillaries ; 

 those teeth, as also the posterior teeth of certain species of 

 the genera Dipsas, Homalopsis, &c., are often grooved, 

 whilst other Ophidians, as the Xenodon, the Coronella, 

 several Homalopsis, &c., have the posterior part of the 

 maxillary furnished with a very large but solid tooth. It 

 is e\ndent that the number of teeth must vary according 

 to the development of the maxillary and the dental bone 

 of the lower jaw. In most of the genus Coluber, each of 

 these branches contain from twenty to twenty -five teeth ; 

 those teeth are less numerous in the Homalopsis, the Tor- 

 trix, the Calamaria, and are reduced to a very few in the 

 venomous serpents. We have stated above, that the 

 maxillary bone of venomous serpents, properly so called, 

 is only armed with the fangs ; but this bone, having a 

 larger development in the colubriform venomous snakes, 

 most frequently carries one or more solid teeth behind 

 the fangs.* 



OF THE GLANDS. 



The salivary glands of serpents present sensible modi- 

 fications in size, situation, and form, not only in the 

 different genera of this order, but also in different species. 

 Their volume is invariably greater in innocuous species than 

 in those also furnished with a poison gland. The glands 

 are denominated from their position ; as nasal, lachrymal, 

 &c. ; and we subdivide those about the jaws into maxillary 

 and mandibular. All these salivary glands, although of 



* The Tropidonotus rudis presents a very singular anomaly in the 

 presence of points of enamel in the guise of teeth, placed on the extre- 

 mities of the inferior spinous processes of the seven or eight last verte- 

 brae towards the head. These teeth are directed backwards, and recall 

 those of the Cyprinus and of certain Crustacea ; but their use, to judge 

 by their direction, is perhaps analogous to that of the conical appendages 

 of the oesophagus in marine Tortoises. They perforate the tunics of the 

 oesophagus, and shew themselves distinctly in the interior of the canal, 

 even in very young subjects. 



