124 Dr. A. Giinther on new Species of Snakes 
densely and regularly punctured, violet-brown in colour; the 
rest of the surface is ashy-white, sparingly punctured; each 
elytron has two or three incomplete raised lines, along each of 
which is a row of very small linear pencils of dark-coloured hair. 
Body beneath and legs black, clothed with ashy pile. 
This species I found at Caripi, near Para. It is closely allied 
to the preceding, and is probably a variety of it; but its much 
smaller size, different coloration and punctation, give it so di- 
stinct a character that, in the absence of connecting links, I am 
obliged to treat it as a separate species. 
The present genus terminates the succession of generic forms 
which lead from the Acanthoderes type to that of Acanthocinus 
and Letopus. I shall now return to a series of forms which ap- 
pear to have branched off from Acanthoderes, especially from 
those species resembling Pteridotelus in general structure. 
[To be continued. ] 
XV.—On new Species of Snakes in the Collection of the British 
Museum. By Dr. Abert GUNTHER. 
[Concluded from p. 59.] 
Narrix. 
Physiognomy entirely that of Tropidonotus. Body stout, cy- 
lindrical ; belly rounded; tail rather long. Temple shields of 
moderate size. Scales smooth, in 19 rows, without apical groove; 
anal entire, subcaudals two-rowed. ‘Teeth of equal length, not 
grooved, of moderate length. 
Natriz levissima. P). IX. fig. 4. 
We have employed for this new genus an old name well 
adapted for the snakes of the family of Natricide, but entirely 
abandoned by later herpetologists, and superseded by that of 
Tropidonotus. ‘The present species has so completely the phy- 
siognomy of Tropidonotus, that we may be justified in giving a 
very short description. The anterior frontals are small, triangular, 
somewhat pointed anteriorly; two nasals, nostril between; a 
large loreal ; one anterior and two posterior oculars ; six rhombic 
temporals, the anterior in contact with the lower ocular only ; 
eight upper labials, the eye over the fourth, the fifth slightly 
entering the orbit. Scales quite smooth, rhombic, in 19 rows. 
Ventrals 175; anal 1; subcaudals 76. Upper and lateral parts 
uniform blackish ash ; ground-colour of the abdomen yellowish ; 
a blackish band commences at the throat, and, gradually be- 
coming broader and more irregular, covers nearly entirely the 
