79. HETERODON. 153 
Total length 285 millim.; tail 45. 
Southern Brazil. 
a-b. 3 (V. 188; C. 83) Cio Cahy, near S. Dr. H. v. Ihering [C.]. 
& her. (V. 133; 0.27). Joao de Monte 
Negro. 
3. Lystrophis semicinctus. 
Heterodon semicinctus, Dum. § Bibr. vi. p. 774 (1854) ; Jan, Arch. 
Zool, Anat, Phys. ii. 1863, p. 224, and Icon. Gién. 48, pl. iii. fig. 5 
(1876). 
pulcher, Jan, Ul. ec. p. 222, Icon. 11, pl. iv. fig. 1 (1865). 
Frontal as long as broad, shorter than its distance from the end 
of the snout, as long as the parietals; usually an azygous shield 
separating the preefrontals ; one or two pre- and two postoculars ; 
temporals 1+2; eight upper labials (exceptionally seven), fourth 
and fifth entering the eye; four or five lower labials in contact 
with the anterior chin-shields; posterior chin-shields small. Scales 
in 21 rows. Ventrals 153-173; anal divided; subcaudals 25-41. 
End of tail rounded off. Above with black cross bars disposed in 
pairs, the interspace between the two yellow, that between the pairs 
red ; the red scales, and sometimes also the yellow ones, with a black 
spot or a black edge; head variegated with black; a black band 
between the eyes; belly black, usually yellow on the sides. 
Total length 660 millim.; tail 80. 
Uruguay, Bolivia, Argentina, Northern Patagonia. 
a. 3 (V. 156; C. 30). Uruguay. 
b. 2 (V. 153; C. 26). Rio de Cordova, E. Fielding, Esq. [P.]}. 
Argentina. 
ec. 3 (V. 162; C. 36). Catamarca. Lord Dormer [P.]. 
d-e. Yg. (V. 159, 154; Argentina. K. W. White, Esq. [C.]. 
C. 33, 30). 
f-g- 2 (V. 160; C. 27) Patagonia. 
' & hgr. (V. 162; C. 25). 
79. HETERODON. 
Heterodon, Latreille, Hist. Rept. iv. p. 32 (1800); Baird § Gir. 
Cat. N. Am. Rept. p. 51 (1853) ; Cope, Proc. U.S. Nat. Mus, xiv. 
1892, p. 642. 
Heterodon, part., Schleg. Phys. Serp. ii. p. 96 (1837) ; Dum. & Bibr. 
Erp. Gén. vii. p. 764 (1854) ; Giinth. Cat. Col. Sn. p. 82 (1858) ; 
Jan, Arch. Zool. Anat. Phys, ii. 1863, p. 218; Bocourt, Miss. Sc. 
Mex., Rept. p. 603 (1886). 
Maxillary very short, shorter than the ectopterygoid, with 6 to 
11 teeth, followed, after an interspace, by a pair of strongly enlarged 
fangs ; mandibular teeth subequal. Head scarcely distinct from 
neck; snout very short, projecting, cuneiform ; rostral very large, 
trihedral, with sharp A-shaped edge; eye moderate, with round 
