2 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
ing out the Solenoglypha, which is also eurystomatous. Peropoda is not in 
Duméril’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: 
; 9. Viperidce ; 
5. Uropeltide 8. Amblycephalidz 
7a, CO, Opisthoglypha 7b.C. Proteroglypha 

4. Llysiidas pee ie 7. Colubridae Aglypha 
. Xenopeltide 
1. Typhlopidz 3. Boidae 2, Glauconiida 
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 DONG raters ai nnrecers reveal siatevsre oteka taro tare topete Typhlopide. 
Maxillary bordering mouth, forming a suture with premaxillary, 'pre- 
frontal and frontal, toothless; lower jaw toothed; pubis and 
ischium present, latter forming a symphysis.......... Glauconiide. 
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 ...... sh. .cisesnenness Boide. 
Squamosal small, intercalated in cranial wall................. Ilysuide. 
ay Norvestiges) of limbs: squamosaljabsent rer sjeereeceietrleik miter te Uropeltide. 
B. Coronoid absent; squamosal present. 
1. Maxillary horizontal; pterygoid reaching quadrate or mandible. 
Prefrontal bone an) contact withaasaliey ss. - sjel)ielyronel Xenopeltida, 
Erefrontalimot iniicontactswathamasaly a. meets eto he atte istoreiel= Colubride. 
2. Maxillary horizontal; pterygoid not reaching quadrate or man- 
CUBE) Ae) S38 S cose eee ier eee eae CemeaEe | Amblycephalide. 
3. Maxillary vertically erectile, perpendicularly to ectopterygoid; ptery- 
goid reaching quadrate ommandibley emacicnercceas Viperide. 
Apart from these anatomical characters the following synopsis will serve 
better for ordinary practical purposes: 
Typhlopide: Eyes vestigial; no teeth in lower jaw; without enlarged ventral scales. 
Glauconiide: Eyes vestigial; teeth restricted to lower jaw; without enlarged ventral scales. 
Uropeltide: Eyes very small; head not distinct; ventral scales scarcely enlarged; tail 
extremely short, ending obtusely and covered with peculiar scales. 
Ilysiide: Eyes functional and free; claw-like spurs of vestiges of the hind limbs on 
each side of vent; ventral scales scarcely enlarged. 
Boide: Eyes functional and free; claw-like spurs of vestiges of hind limbs on each 
side of vent; ventral scales transversely enlarged. 
Xenopeltide: 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. 
Amblycephalide: Like the Xenopeltide, but ends of pterygoids free, not reaching the 
quadrates. No mental groove. 
Colubride: Like the Xenopeltide in main characters, but squamosal horizontally 
elongated and movable; pterygoid reaches the quadrate. Median longitudinal 
line between shields of chin. 
Viperide: Eyes free; pair of poison fangs in front part of mouth, carried by the other- 
wise toothless, much shortened, and vertically erectile maxillaries. Ventral scales 
transversely enlarged. 
