62 Contribution towards the knowledge of snakes in Brazil 
IV 
Lachesis insularis n. sp. 
(Plates IV and Ill; figs. 1-5) 
Number of specimens — 2083. 
Description — Head very wide in the temporal region; snout 
relatively short and narrow; body, slender and somewhat flattened 
laterally; tail short and slightly prehensile. 
Snout rounded and narrow; canthus salient and slightly raised. 
Rostral narrow, a little deeper than broad. Internasals generally 
in contact with behind the rostral, with a slight sulcus. Canthal 
more or less plain, slightly inclined outwards, about twice as 
long as broad, and generally as long as and a little broader 
than the internasal. Supraocular small, about twice as long as 
broud, slightly inclined outwards, smooth or rugous, and nearly 
always entire (only two specimeus, n.ºs 1.857 and 1.903, show 
it divided transversally). Scales of the upper part of the head 
small, keeled, imbricated and in 7 longitudinal rows between the 
supraoculars (among the 203 specimens, 26 have 6, 24 have 8, 
2 have 5 and 1 has 9 rows), generally substituted on the anterior 
part, between the canthals, by a pair of large scales, like shields, 
juxta-posed, nearly always smooth and separated anteriorly by 
another large scale, azygous, placed in the angle of the in- 
ternasals, the three of which are sometimes surrounded by minute 
scales. Nasal divided. Pree-oculars 2, the superior, which is larger, 
reaching the canthus. Postoculars 2 (46 specimens have only 1 
on the right, and 40 have only 1 on the left, 4 have 1 on 
the righi and left, and 6 have 3 on the left, 5 have 3 on the 
right, and 1, n.º 1.898, has no postocular on the right). Only 
one subocular, separated from the upper labials by a row of 
scales (in 29 specimens there are two rows to the left and in 
16 there are 2 rows to the right). Temporals, all strongly keeled. 
Upper labials 8 (25 specimens have 9 on the right, 23 have 9 
on the left and 11 have 9 on both' sides), the 2nd. in contact 
with the pra-loreal, and forming the anterior border of the 
loreal pit on both sides of the 203 specimens (10 instances it 
is not forming on the right, in 10 it is not forming on the left, 
and im 21 it is not forming on either side). Scales in 25 lon- 
gitudinal rows (except 37 specimens 9 £ which have 27 rows; 
4 which have 24 rows; and 24, 19 being JJ, which have 23 
rows), all markedly keeled from the head to the end of the 
tail, The keel, which is high and long, extends to the posterior 
extremity of the scales. Ventrals 171-195, 171-188 being the number 
in specimens & q and 176-195 in specimens Z 2. Anal entire. 
Subcaudals 48-65, 55-65 being the number in specimens & &, and 
48-59 in specimens 2 2, all paired or some entire especially 
in specimens 2 2, as can be seen by annexed table (List of 
specimens). 
