1. @ERRHONOTUS. 267 
Synopsis of the Species. 
I. Dorsal scales larger than ventrals. 
A. An azygos prefrontal shield. 
1. Nuchal scales in four longitudinal series. 
No granular zone in the lateral fold; no 
fold along the side of the neck ...... 1. owxace, p. 268. 
Lateral fold enclosing granules; a slight 
fold along the side of the neck ...... 2. gramineus, p. 269. 
2. Nuchal scales in six or more longitudinal series. 
a. No projecting scales above the ear. 
Azygos prefontal completely enclosed be- 
tween two pairs of prefrontals; 13 or 
14 longitudinal series of ventrals .... 3. deppu, p. 269. 
Azygos prefrontal separated from the 
loreal by a small canthal shield; ven- 
trals in 12 longitudinal series........ 4. teniatus, p. 270. 
b. A series of projecting scales above the ear. 
Dorsal scales in 12 or 13 longitudinal 
BCLlCS sas wawessorwceewsesar ds eae 5. vasconcelosii, p. 270. 
B. No azygos prefrontal. 
1. A series of projecting scales above the ear. 
Four pairs of shields between the frontal 
and the rostral.... 0... 6... cece eee 6. fimbriatus, p. 271. 
Three pairs of shields between the frontal 
and the rostral... 0... cece eee 7. auritus, p. 271. 
2. No projecting scales above the ear. 
35 to 40 transverse series of dorsal scales 
between the head and the base of the 
tail, and 12 or 14 longitudinal series... 8. imbricatus, p. 272. 
27 transverse series of scales .......... 9. rudicollis, p. 272. 
16 longitudinal series of dorsal scales.... 10. planifrons, p. 273. 
II. Dorsal scales not or but scarcely larger than ventrals. 
A. Lateral dorsal scales keeled. 
Dorsal scales in 14 or 16 longitudinal 
BCrieS) vaseih ap duea whe deaae sey 11. ceruleus, p. 2738. 
B. Lateral dorsal scales smooth. 
1. An azygos prefrontal, separated from the frontal by a pair 
of prefrontals, 
