146 
ON THE PHYSIOONOMY OP SERPENTS. 
nated scales, disposed in 21 rows ; by a slender tail ; and 
by tints of a yellow, verging sometimes to brown, some- 
times to green. The bead is of a brownish-red, and its 
posterior parts often dark coloured, while the abdomen is 
yellowish : the female has the lower part of the head reddish. 
The eye is large, and bordered posteriorly by three plates. 
Inhabits marshes in deep forests, and in manners ap- 
proaches the Tropidonotus. 
17 . Coluber Canus, the only species of the genus 
known in southern Africa, in its organization resembles the 
Psammophis, or sand-serpents ; head small and conical ; 
muzzle terminated by a salient, vaulted plate ; eyes rather 
large ; scales small, truncated at the top, smooth, and dis- 
posed in 27 rows ; tail short and thick. Its anatomy 
presents several curious particulars : the penis is double 
at each side, the cranium has the form of that of the Her- 
petodryas, the mastoid bones are extremely large, and the 
strong teeth become longer towards the extremity of the 
muzzle. Size large, even six feet. S. 194 + 64. This 
curious species is also remarkable for the changes which 
the colours undergo by age — pale reddish-brown, relieved 
by four ranges of ocellated spots, in the young ; grey, in- 
clining to olivaceous, or to brown or black, in the adult. 
18. Coluber Sayi. From Missouri. Head very conical ; 
vertical plate triangular in form ; rostral salient ; 25 rows 
of carinated scales ; reddish-yellow, the back a deep 
browm ; these colours form spotted bands. S. 224 + 55. 
19. Coluber auATERRADiATUs. Sometimes of the 
length of seven or eight feet ; lives in the south of Europe ; 
head distinct from the trunk, very elongated, high near the 
eyes ; muzzle thick ; eye large, overshadowed by a pro- 
jecting plate ; occipital plates pointed ; tail strong ; 25 
rows of small lanceolate scales. S. 212 + 75. Above 
brown, relieved by four brown rays more or less distinct ; a 
dusky ray passes from the eye to the angle of the mouth. 
This Coluber is very gentle in its manners. 
20. Coluber viridielavus. From the same regions 
as last, but of a larger mould, more widely distributed, and 
more common. Tail very slender, and hat below ; trunk 
almost cylindrical ; abdomen convex ; 19 rows of smooth 
