188 11EPTILIA : OPIIIDIA. — XXVIII. 



bones of both jaws and of the palato-pterygoid arch freely movable, 

 united by ligaments only. Limbs wanting; the shoulder girdle 

 wanting ; tbe pelvic girdle usually so, rarely rudimentary, and with 

 the binder limbs represented by small spurs on the sides of tbe 

 vent; vent a transverse slit; tongue forked, capable of protrusion ; 

 no evelids, nor external ears. Various anatomical characters dis- 

 tinguish tbe snakes, but tbe elongated form and absence of limbs 

 separate tbem at once from all our other vertebrates, excepting the 

 lizard Ophiosaurus, and this is not in any other respect, snake-like. 

 (6'<£ij, snake.) 



Families of Ophidia. 



a. Maxillarv horizontal, not excavated; no trace of hinder limbs; no deep 

 pit between eye and nostril ; poison fangs wanting, or if present, per- 

 manently erect. 

 6. Upper jaw with solid teeth only; no grooved nor perforated fangs. (A r OK- 



venomous.) Colubrid^e, 110. 



bb. Upper jaw with a permanently erect perforated fang in front. (Somewhat 



venomous.) Elapid.e, 111. 



aa. Maxillary vertical ; upper jaws in front with, large, erectile perforated 

 fangs; fangs not grooved in front; a deep pit on each side behind 

 nostril, partly occupying the excavated maxillary. ( Venomous.) 



Crotalid^e, 112. 



Family CX. COLUBRID^E. (The Coltjbkine Snakes.) 



Both jaws fully provided with teeth, which are conical and not 

 grooved ; head covered with shields ; no poison fangs ; no spur-like 

 appendages to vent; belly covered with broad band-like plates 

 (ventral plates or gastrosteges) ; tail conical, tapering ; sub-caudal 

 plates (urosteges) arranged in pairs. 



A very large family comprising 225 genera, and upwards of 700 

 species, found in nearly every part of the world, but most abundant 

 in warm regions. They differ from the Elapidce in the want of 

 erect poison fangs; from the Crotalidce, in having both jaws fully 

 provided with teeth, and in the absence of erectile poison fangs ; and 

 from the Boidce and their relatives in the want of the spur-like ru- 

 dimentary posterior limbs. 



a. Head conic, not distinct from the bod}-, which is cylindric and rather 

 rigid. (Calamariinai.) 

 b. None of the teeth grooved; scales not keeled; anal plate bifid; inter- 

 nasals 2. 

 c. Prefrontals 2. 

 d. Nasal plate single, pierced by the nostril; lorals present; no pre- 

 ocular. 

 e. Scales in 13 rows; postorbital single (ventral plates 120 to 135). 



Carphophiops, 269. 

 ee. Scales in 19 rows; postorbitals 2 (V. P. 170 to 185). 



Abastor, 270. 



