SYSTEMATIC ACCOUNT OF THE SPECIES. 193 
not much more than half the length of the parietals; loreal almost twice as 
long as high; two pre- and two postoculars; temporals 1 + 2; eight upper 
labials, the fourth only entering the eye; four lower labials in contact with the 
anterior chin-shields, three with posterior; posterior chin-shields a very little 
longer than the anterior and separated from each other by four scales; scales 
keeled in nineteen rows; ventrals 163, anal divided, subcaudals fifty-seven. 
Colour (in life): —Grayish olive above with dark slaty, almost black, 
cross-bands, the first sending an extension forward to the posterior border of 
the parietal shields; a dark streak on each side of the head; below bluish gray 
marbled and flecked with whitish. 
This species is remarkably uniform in colouration. A few variations occur 
among the head scutes, thus the preoculars may be fused into a single scale; 
five instead of four lower labials may be in contact with the anterior chin-shields. 
From various sources we find the range of counts to be ventrals 131-167; anal 
divided; subecaudals 48-81. Boulenger (Cat. snakes, Brit. mus., 1893, 1, 
p. 282) says: — 
“Olive or blackish above, with or without blackish cross-bands; a more or less distinct 
light lateral streak on the second and third rows of scales; a dark streak on each side of the 
head, passing through the eye; belly orange or red, dotted or spotted all over with brown 
or brown dotted with pale.” 
These remarks are very far from being in accord with our considerable experi- 
ence of this snake in the field. We have never seen a blackish example, nor one 
lacking the cross-bands, nor one with red or orange on the belly. Boulenger 
had but three specimens before him when he wrote the Catalogue and they were 
probably badly preserved. The white lateral band, he mentioned, is always 
found in the young, but we have never observed it on adults. In the young 
also the dark cross-bands appear as oblong or squarish dorsal patches which 
become extended into the strap-like bands with increasing age. 
The Catibo or Quimbélo is wholly aquatic and also strictly nocturnal. By 
day it may be found hiding beneath stones or in accumulations of drift vegeta- 
tion, especially in the torrential mountain brooks. In these streams it occurs 
quite abundantly, as in the more slowly flowing rivers or lagoons and lakes 
choked with water plants. It is absolutely inoffensive and the largest indi- 
viduals never open their mouths to bite when caught, nor offer the slightest 
resistance. In the early morning or at dusk they may sometimes be seen partly 
emerged from their lair, with their heads near the surface of the water. They 
appear to breathe at the surface at very long intervals and we have never seen 
