os 
COLUBRIDA. — CX. 189 
dd. Nasal plates 2, the nostril between them; a loral plate; no preocu- 
lar; (scales 15 or 17, V. P. 115 to 125). . . . Vurernra, 271. 
cc. Prefrontal single; no preocular; nasal single; (scales 19; V.P.170 to 
ZRF... iy-) <=. RA Oe OP een Pisa ora, 879, 
aa. Head more or less distinct from the body which is not specially rigid 
(Coronelline,! Colubrine, Homalopsine). 
J. Rostral plate normal, not recurved nor keeled. 
g. Anal plate divided ; head not very short. 
h. Dorsal scales keeled more or less. 
7. Nasal plates 2, the nostril between them. 
j- Prefrontals 2. 
k. Loral plate present. 
i. Scales on back and sides all keeled (ventral plates 130 to 170). 
m. Posterior teeth not longer (scales 19 to 21). . REGINA, 277. 
mm. Posterior teeth longer (scales 23 to 31). 
TROPIDONOTUS, 278. 
Il. Scales on sides not keeled; those on back often with the 
keels obscure (V. P. 200 to 270; scales 25 to 29). 
CoLUBER, 279. 
kk. Loral plate absent (scales 15 to17; V. P. 125 to 130). 
STORERIA, 274. 
Jj. Prefrontal single; nasals 2; loral present ; no preocular (scales Lis 
V. P. 120 to 130); body gender the head distinct. 
HALDEA, 273. 
zi. Nasal single, pierced by the nostril; loral plate present. 
n. Nasal plate grooved; tail short (scales 19; V. P. 130 to 
Be) yas ea he Hye! tie TROPIDOCLONTUM, 275. 
nn. Nasal plate not srpbved below nostril; tail very long, 
about $ of length (scales 17; V. P. 150 to 160). 
CycLopuis, 280. 
hh. Dorsal scales not keeled. 
o. Nasal single, pierced by the nostril; loral present; tail 
long (scales 15; V. P. 125 to 140). LiorEetris, 281. 
oo. Nasal plates 2, the nostril between them; loral pres- 
ent; preoculars 2. 
p. Head depressed; preoculars nearly equal in size 
(scales 15 to 17; V. P. 140 to 200 or more), 
Diapopuis, 284. 
pp. Head not depressed; upper preocular much the 
larger; lower sometimes wanting ; (scales 17; V. 
P. 170 to 210), . . . . « BAscanton, 282. 
gg. Anal plate entire. 
g- Dorsal scales all or part of them keeled; head 
rather long. 
1 These three sub-families are so vaguely bounded that I cannot use their distinc- 
tive characters in the key. Professor ps gives the following definitions : — 
Homalopsine. (Genera 273 to 278.) ‘* Hypapophyses spinous to caudal region; an- 
terior teeth not enlarged; body not slender; head distinct. 
Colubrine. (Genera 279 to 283.) Head more distinct and elongate; body and tail 
longer; teeth entire, not longer in front, 
Coronelline. (Genera 284 to 288.) Head slightly distinct, short ; teeth entire, 
not enlarged in front. 
