SNAKES. 19 



not very long, and its channel generally visible as an external 

 groove. Poisonous Snakes with such a dentition resemble also in 

 other respects the non-venomous Serpents, and are designated as 

 Venomous Colubrine Snakes. 



In the other venomous Snakes the maxillary bone is extremely 

 short, and does not bear any ordinary teeth, only an exceedingly 

 long curved fang, perforated in its entire length. Although this 

 tooth also is fixed to the bone, the bone itself is very mobile ; so 

 that the tooth, which is laid backwards when at rest, can be 

 erected the moment the animal prepares to strike. The tooth is 

 occasionally lost ; but others, in different stages of development, 

 lie in the gum behind it, ready to take the place of the lost tooth. 



Most Snakes feed on living animals, a few only on eggs. They 

 are oviparous or ovoviviparous. They number about 1800 species, 

 and are spread over all temperate regions, but are most numerous 

 between the tropics. They are absent in New Zealand. The 

 Order is divided into three Suborders and numerous minor groups. 



Suborder I. Ophidii Colubriformes. 

 (Innocuous Snakes.) 

 Typhlopidae (Burrowing or Blind Snakes) ; Stenostomatida, 

 Tortricidce, Xenopeltida, Uropeltida, Calamariidce, Oligodontidce, 

 Colubridce, Homalopsida (Freshwater Snakes) ; Psammophidce 

 (Sand-Snakes) ; Dendrophidce (Tree-Snakes) ; Dryiophidce, Dipsa- 

 did(B, Scytalidoe, Lycodontidce, Amblycephalidce, Pythonidce, Boidce, 

 Erycida, Acrochordidce. 



Suborder II. Ophidii Colubriformes venenosi. 



(Venomous Colubrine Snakes.) 

 Cobras and Coral Snakes (Elapidcs) and Sea-Snakes (Hydro- 

 phidae). 



Suborder III. Ophidii Viperiformes. 



(Viperine Snakes.) 

 Vipers (Viperida), Pit-Vipers, and Rattlesnakes (Crotalidce) . 



Snakes are most unsuitable objects for preservation in a dry 

 state, as no method is known by which the singularly regular 



