DESEET SNAKES. 53 



the European Colubrida, and, like the others, it is found in 

 most parts of Europe. 



[The Psammopkidce, or Desert Snakes, are akin both to the 

 Colubridce and to the Tree Snakes of the next family ; but the 

 latter, remarks Dr. Giinther, may always be distinguished either 

 by their green coloration, by the horizontal pupil to the eye, or 

 the absence of a long, anterior, maxillary tooth. In the Psammo- 

 phidce the pupil of the eye is round or vertical. Most of the 

 species of this family belong to the fauna of tropical Africa, which 

 also produces a slender form (in Psammophis elegans). The other 

 species are of a stouter habit, frequenting plains, or at all events 

 living on the ground. Of the Indian Psammophis condanarus, 

 Dr. Jerdon procured one which had killed and was swallowing a 

 small Yiper (Echis carmata), this being one of the few instances 

 in which a non-venemous Snake has been known to overpower a 

 poisonous one. We have heard the same of a small Boa-like 

 Serpent (Chilabothrus?) in the West Indies, which is said to 

 prey upon the formidable Crotatidte. The Psammodynastes 

 puherulentus has a wide geographical range over South-eastern 

 Asia and its islands. Although innocuous, it has the aspect of a 

 venemous species. 



In a kindred African family, the Rachiodontida, the species of 

 Dasypeltis have the maxillary teeth minute and few in number 

 (four to seven) ; but they have also some remarkable gular teeth, 

 which are formed by the elongated inferior spinous processes of 

 the hinder cervical vertebrae. The object of the latter is to crush 

 the shells of birds' eggs, upon which the Snakes in question 

 habitually feed. 



Of the more characteristic Tree Snakes, the Dendrophidcz have 

 the body and tail much compressed, or very slender and elongated ; 

 the head generally lengthened,, narrow, flat, and distinct from the 

 slender neck ; the snout rather long, obtuse or rounded in front ; 

 cleft of the mouth wide ; and the eye of moderate size, or large, 

 with round pupil. These are Diurnal Snakes, which live entirely 

 upon trees, where they prey chiefly on arboreal lizards and frogs. 

 Species of them inhabit all tropical countries. They are mostly 

 of great beauty, and the Indian Ckrysopelea ornata is excessively 

 so, being variegated with yellow and crimson upon a black ground ; 



