2560 SCALED REPTILES 



THE COLUBRINE SNAKES 

 Family COLUBRID^ 



The skulls of the remaining snakes are markedly distinguished from those of 

 the foregoing by the total absence in the lower jaw of the bone known as the 

 coronoid; while in all cases a supratemporal is present on the upper surface of the 

 skull. The present family, which includes by far the greater majority of the species 

 of the suborder, and comprises both harmless and noxious kinds, is specially 

 distinguished from those to be mentioned later on by the circumstance that in the 

 skull the upper jawbone, or maxilla, is fixed in a horizontal position, and also that 

 the pterygoids reach either to the quadrate bone or the lower jaw. 



Before coming to the Colubrine family it should, however, be mentioned that 

 there is one remarkable snake {Xenopeltis imicolor) from Southeastern Asia retain- 

 ing in the structure of its skull traces of affinities with the boas and pythons. This 

 affinity is displayed by the fact that the pref rental bone, which lies immediately 

 behind the nasal aperture of each side, is of large size and extends forward and 

 inward to articulate with the nasal bone in the same manner as the boas. Accord- 

 ingly, this snake is regarded as the representative of a distinct family {Xenopeltidce) , 

 which is considered to have originated from the Boidce quite independently of the 

 Colubrines. 



From Xenopeltis the Colubrines are distinguished by the small size of the 

 prefrontal bone of each side, which articulates merely to the outer front angle of 

 the frontal bone without any contact with the nasal bone. In such a large group 

 it is highly important to have some means of division into subgroups of higher 

 value than genera; and, according to the modern classification, three such serial 

 divisions may be indicated by the characteristics of the teeth. The first and most 

 primitive of these series, which may be termed the solid-toothed colubrines 

 (Aglyphd}, is characterized by the whole of the teeth being solid, without any trace 

 of grooves, all its representatives being harmless. On the other hand, in the second 

 series or hind-fanged colubrines (Opisthoglypha} one or more of the hinder teeth 

 of the upper jaw are grooved; while in the third series or front-fanged colubrines 

 (Proteroglypha'} the front teeth of the upper jaw are grooved or tubular. Of the 

 last series the whole of the members are poisonous, while many of those of the 

 second are noxious in a minor degree. All these three sections contain species 

 adapted to particular modes of life, so that we may have two or three snakes which, 

 while externally very similar, are only distantly allied to one another. 



The Javan wart snake (Acrochordus javanicus) may be taken as a 

 well-known representative of the first, or acrochordine subfamily 

 of the solid-toothed colubrines, which includes only five genera, distributed over 

 Southeastern Asia and Central America. Unfortunately, the characteristics distin- 

 guishing this subfamily from the next are connected with the bones of the skull, 

 and cannot therefore be verified without dissection; but in the study of snakes, ac- 

 cording to the modern system, the student must accustom himself to such difficul- 



