OPHIDIA, 431 



morsels entire. The teeth, namely, are simply fitted for 

 seizing and holding the prey, but not in any way for dividing 

 or chewing it. In the non-venomous and most typical Snakes, 

 the jaws and palatine bones carry continuous rows of solid 

 conical teeth, so that there are four rows above and two below; 

 and the superior maxillae are very long and are not movable. 

 Thirdly, in the Viperine Snakes the ordinary teeth are wanting 

 upon the superior maxillae, whilst these bones are themselves 

 very much shortened, and are capable of being raised and 

 depressed at will. In place of the ordinary teeth, each maxilla 

 carries a " poison-fang," in the form of a long, conical, curved 

 fang, which is concealed in a fold of the gum when not in use, 

 and has numerous germs or reserve-fangs behind it (fig. 166, B). 

 Each tooth is perforated by a tube, opening by a distinct aper- 

 ture at the apex of the tooth, and conveying the duct of the 

 so-called poison-gland. (In reality the poison-duct of the fang 

 is formed by an inflection of the tooth upon itself, and not by 

 its actual perforation.) This is a gland, probably produced by 

 a modification of one of the buccal saUvary glands, situated 

 behind and under the eye on each side, and secreting the fluid 

 which renders the bite of these snakes dangerous or fatal. 

 When the animal strikes its prey, the poison-fangs are erected, 

 and the poison is forced through the tube which perforates 

 each, partly by the contractions of the muscular walls of the 

 gland, and partly by the muscles of the jaws. In most poison- 

 ous snakes the superior maxillse carry no other teeth except 

 the poison-fangs and their rudimentary successors, but in some 

 cases there are a few teeth behind the fangs ; whilst the pala- 

 tine teeth are always present, as in the harmless species. In 

 some other venomous Snakes, again (e.g., Naja and the Hydro- 

 phida), the jaws and teeth agree in most characters with those 

 of the non-venomous Snakes, but the first maxillary teeth are 

 larger than the others, and form canaUculated fangs. Lastly, 

 in a few forms the terminal maxillary teeth are deeply cana- 

 liculated, but are not connected with the duct of any poison- 

 gland. 



Fourthly, in all the Serpents the teeth are anchylosed to the 

 jaw, and are never sunk into distinct sockets or alveoh. 



A good classification of the Ophidia is still a desideratum, 

 and probably, in the meanwhile, the one proposed by Dr Gray 

 is the best. This eminent naturalist divides the Snakes into 

 the two sub-orders of the Viferina and Colubrina, the former 

 having only two perforated poison -fangs on the superior 

 maxillae, whilst these bones in the latter carry solid teeth, 

 either with or without additional canaUculated fangs. 



