77. XENODON. 149 
5. Xenodon severus. 
Coluber severus, Zinn. Mus. Ad. Frid. p. 25, pl. viii. fig. 1 (1754), 
and S. N. i. p. 879 (1766). 
Cerastes severus, Laur. Syn. Rept. p. 81 (1768). 
Coluber breviceps, Shaw, Zool. iii. p. 430 (1802). 
versicolor, Merr. Tent. p. 95 (1820). 
saurocephalus, Wied, Beitr. Nat. Bras. i. p. 359 (1825). 
Xenodon severus, Schleg. Phys. Serp. ii. p. 83, pl. ii. figs. 1-5 (1837) ; 
Dum. §& Bibr. vii. p. 756 (1854) ; Giinth. Cat. p- 54 (1858). 
severus, part., Jan, Arch. Zool. Anat, Phys. i. 1863, p. 317, and 
Icon, Gén. 19, pl. iii. fig. B (1866). 
Maxillary teeth 10-1242. Head short, much depressed ; body 
more or less depressed. Rostral twice as broad as deep, the portion 
visible from above measuring one fourth to one third its distance 
from the frontal; internasals nearly as long as broad, as long as the 
prefrontals or a little longer ; frontal as long as broad or slightly 
longer, as long as or a little shorter than its distance from the 
rostral, shorter than the parietals; loreal deeper than long; one 
pree- and two or three (rarely four) postoculars ; temporals i +2 or 
1+3,; eight upper labials, fourth and fifth entering the eye; five 
or six lower labials in contact with the anterior chin-shields, which 
are larger than the posterior. Scales in 21 rows. Ventrals not 
angulate laterally, 128-149; anal divided: subcaudals 33-42. 
Young with angular, brown, dark-edged bands separated by 
narrow pale brown interspaces ; usually a round white spot on the 
nape, and light and dark curved bands on the head; belly brown or 
black, with large yellowish spots on the sides. These markings 
usually become indistinct or disappear in the adult, some of which 
are pale brownish or greyish above and yellowish inferiorly ; others 
have broad black bands across the body, or black edges to some or 
all of the scales, or the upper parts may be entirely black with a few 
small yellowish spots. 
Total length 1500 millim.; tail 190. 
Tropical South America. 
Yg. (V. 149; C.36). Rosario de Cucuta, Mr. C. Webber [C.]}. 
Colombia. 
b. o (V. 135; C. 36). Venezuela, Mr. Dyson [C.]. 
end. ®: (V: 140, 139; C.38, Demerara. 
38 
e, f. wp (V. mee C. 40) & Berbice. Lady Essex [P. ]. 
Q (V. 140; C. 37). 
q., Ven (V. 134; C. 41). Berbice. 
h. 2 (V. 140; 0. 36). British Guiana. 
Rover: 136; C. 38). Surinam. 
be, Her. Q (V. 189; Para. R. Graham, Esq. [ P.]. 
C. 37) & yg. (V. 142 
C. 40). 
m,n. 3 (V. 134; C. 36) Para. 
ye. (V. 137; C. 34). 
0, OF (Ne 136; C. 34) Moyobamba,N.E. Mr. A. H. Roff [C.]}. 
& ‘hgr. (Viele; AG. 36). Peru. 
