VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



ing out the Solenoglypha, which is also eurystomatous. Peropoda is not in 

 Dume"ril's system, although a Eurystomata. 



Finally, Boulenger succeeded in formulating a more natural and rational 

 classification of these animals, which is accepted by most systematists as by 

 far the best proposed. His phylogenetic system stands as follows: 



5. UropeWdae 



4. llysiidas 



g.Viperidce 



7a, O. OpisV 



ogVypha 



8. Amblycephalidae 

 jb.C. Proteroglypha 



6. Xenopeltidae 



7. Colubridae Aglypha 



Typhlopidae 



3. BoidaB 



2. Glauconiidas 



I. No ectopterygoid; pterygoid not extending to quadrate or to mandible; no 

 supratemporal (squamosal); prefrontal forming a suture with 



nasal; coronoid present; vestiges of pelvis 



Maxillary vertical, loosely attached, toothed; mandible edentulous; a 



single pelvic bone Typhlopidce. 



Maxillary bordering mouth, forming a suture with premaxillary, [pre- 

 frontal and frontal, toothless; lower jaw toothed; pubis and 



ischium present, latter forming a symphysis Glauconiidas. 



II. Ectopterygoid present; both jaws toothed. 



A. Coronoid present; prefrontal in contact with nasal. 



1. Vestiges of hind limbs; supratemporal (squamosal) present. 



Squamosal large, suspending quadrate Boidce. 



Squamosal small, intercalated in cranial wall Ilysiidce. 



i. No vestiges of limbs; squamosal absent Uropeltidce. 



B. Coronoid absent; squamosal present. 



1. Maxillary horizontal; pterygoid reaching quadrate or mandible. 



Prefrontal bone in contact with nasal Xenopeltidce. 



Prefrontal not in contact with nasal Colubridac. 



v. Maxillary horizontal; pterygoid not reaching quadrate or man- 

 dible ) Amblycephalidce. 



3. Maxillary vertically erectile, perpendicularly to ectopterygoid; ptery- 

 goid reaching quadrate or mandible Viperidce. 



Apart from these anatomical characters the following synopsis will serve 

 better for ordinary practical purposes: 



Typhlopidce: Eyes vestigial; no teeth in lower jaw; without enlarged ventral scales. 



Clauconiidce: Eyes vestigial; teeth restricted to lower jaw; without enlarged ventral scales. 



UropeltidiE: Eyes very small; head not distinct; ventral scales scarcely enlarged; tail 

 extremely short, ending obtusely and covered with peculiar scales. 



Ilysiidce: Eyes functional and free; claw-like spurs of vestiges of the hind limbs on 

 each side of vent; ventral scales scarcely enlarged. 



Boidce: Eyes functional and free; claw-like spurs of vestiges of hind limbs on each 

 side of vent; ventral scales transversely enlarged. 



Xenopeltidce: Eyes free; no vestiges of limbs or of their girdles; maxillary typical, hori- 

 zontal, not separately movable, with a series of teeth; mandible toothed, but no 

 coronoid bone. Dentary movably attached to tip of articular bone of mandible; 

 skin beautifully iridescent. 



Amblycephalidce: Like the Xenopeltidx, but ends of pterygoids free, not reaching the 

 quadrates. No mental groove. 



Colubridce: Like the Xenopeltidce in main characters, but squamosal horizontally 

 elongated and movable; pterygoid reaches the quadrate. Median longitudinal 

 line between shields of chin. 



Viperidce: Eyes free; pair of poison fangs in front part of mouth, carried by the other- 

 wise toothless, much shortened, and vertically erectile maxillaries. Ventral =cales 

 transversely enlarged. 



