Animals called, by Linnaeus, Amphibia. a; 
With refpedt to thofe Colubri which are not venomous, it 
muff be confeffed, that there are many whofe tails are within 
the limits affigned to the venomous ones. In the Coluber ^Efcu- 
lapii, doliatus, getulus, and fome others, the tail is not, in 
general, more than one-feventh of the whole length. In the 
lemnifcatus I have found it not exceeding one-twelfth or 
thirteenth; but I know no other Linnaean fpecies in which it 
is fo fhort. In the greater number, however, the proportion of 
tail is more confiderable ; in many, it is full one- third. In the 
Ahaetulla, and in fome fpecies not defcribed by Linnaeus, I 
have feen it more than two-fifths ; but have never met with a 
fpecies in which it was quite fo long as the trunk, or half 
of the whole length. 
I have not confidered the Bose, becaufe none of the Linnaean 
fpecies, of that genus, have their tails either remarkably long, 
or (hort; but, in two fpecies, not defcribed by Linnaeus, I 
found the tail very little exceeding the proportion I have affigned 
to the Coluber lemnifcatus. 
In the thicknefs of the tail, or in the acutenefs of its termina- 
tion, I have obferved no difference worth remarking. In every 
fpecies of the three firft genera, the tail is thinner than the trunk ; 
and in mod of them it is more or lefs acute. The few exceptions 
I have obferved were, I believe, none of them venomous ; but 
they are too few to deferve any particular conff deration. 
A character of great ufe in diftinguifhing the fpecies of Ser- 
pents, and which was not overlooked by Linnaeus, is, that 
elevated line, or carina, with which the fcales of many fpecies 
are furnilhed. In order to fhew how far this is to be confidered 
as ferving to diftinguifh venomous Serpents from others, I 
need only obferve, that I have examined one hundred and twelve 
fpecies of Serpents, not venomous, belonging to the three firft 
E z genera ; 
