190 REPTILIA : OPHIDIA. — XXVIII. 
r. Postfrontals 2 pairs; loral single; prefrontals 4 or more (scales 25 to 
35; V..P..200 to 250).: 8. 2 ial ee OGRE eee 
rr. Postfrontals 1 pair; nasals 2; posterior teeth rather larger; vivipa- 
rous (scales 19 to 21; V. P. 140 to 180). . . . EUTAINIA, 276. 
qq. Dorsal scales not keeled, rather loosely imbricate; head short (V. P. 
160 to 240). 
s. Rostral plate not acute. 
t. Loral present (scales 21 to 25). . . . . . . OPHTBOLUS, 285. 
tt. Loral absent (scales 19) .. . a 0 ads) SOSGROELA Zee. 
ss. Rostral plate acute, the snout sharp- ainbed (scales 19). 
CEMOPHORA, 287. 
ff. Rostral plate (at tip of snout) produced, recurved and keeled; dorsal 
scales keeled; anal plate divided ; head broad and short; some of the 
posterior teeth enlarged (scales 23 to 27; V. P. 120 to 150). 
HETERODON, 288. 
The following purely artificial key may aid in finding the names 
of specimens : — 
I. Dorsal scales not keeled ; anal plate bifid. 
a. Scales 13; V. P. about 130; color brownish . CARPHOPHIOPS, 269. 
aa. Scales 15 to 17. 
b. Ventral plates about 120; brownish. . . . . Vuirernta, 271. 
bb. V. P. about 140. 
c. Blackish, with yellow collar. - » » » » DIADOPHIS,/ 282: 
ce. Green; necollar, “. . « . « LIoperss, 281; 
bbb. V. P. about 185; blue-black, Bas blotched. BASCANION, 282. 
aaa. Scales 19; V. P. show 180. 
d. Blue-black with three red lines. . . . . . ABASTOR, 270. 
dd. Blue-black with square red spots on sides. . . FARANCIA, 272. 
aaaa. Scales 25 to 29 (median dorsal scales faintly keeled). 
. CoLUBER, 279. 
II. Dorsal scales not at all keeled; anal plate entire. 
e. V. P. about 170 to 205; snout not sharp. 
J. Scales 19; red, black-banded. . . . -... . OSCEOLA, 286. 
Jf. Scales 21 to 25; black, brown or red, mostly variegated. 
OPHIBOLUS, 285. 
ee. V. P. 160 to 170; scales, 19; snout sharp; red with black rings. 
CEMOPHORA, 287. 
III. Dorsal scales more or less keeled; anal plate entire. 
g. Scales 19 to 21; V. P. about 155; striped . . . EuTarntA, 276. 
gg. Scales 25 to 35; V. P. about 220; blotched . . Prirvopuis, 283. 
IV. Dorsal scales keeled; anal plate bifid. 
h. Scales 15 to 17. 
?. Tail about } of length; V. P. 155; green. . .CYCLOpPHis, 280. 
ii. Tail not $ of length; brownish. 
j- Loral absent... i'd ae ee oe Oa re 
jj. Loral present. 3) 2S ae ea Se) a ee 
hh. Scales 19 to 21. 
k. V. P. about 135; blotched. . . . . TROPIDOCLONIUM, 275. 
