Animals called , by Linnjeus, Amphibia. 29 
Anguis affords\examples of much lefs proportion, and alfo of 
much greater, than is to be found in any of the three ,firft 
genera. In the An guts Scytale the tail is not above one-twen- 
tieth of the whole length ; in the maculata it is not above one- 
fortieth ; yet in the Anguis fragilis, and in the ventralis, the 
tail is always longer than the trunk, or, in other words, is more 
than half the whole length. Indeed, in one fpecimen of the 
laft mentioned fpecies, I found the tail nearly two-thirds of the 
whole length. It may, however, be queltioned whether that 
fpecies is really an Anguis, or a Idacerta*. 
I fhall make na further remarks oirthe external characters of 
Serpents ; the principal inferences to be deduced 'from thofe I 
have already made, are the following. 
lft, That a broad head, covered with fmall fcales, though 
it be not a certain criterion of venomous Serpents, is, with 
fome few exceptions, a general character of them. 
2dly, That a tail under one- fifth of the whole length, is alfo 
a general character of venomous Serpents; but, fince many of 
thofe which are not venomous have tails as (hort, little depen- 
dance can be placed upon that circumfbrnce alone. On the 
other hand, a tail exceeding that proportion, is a pretty certain 
mark that the fpecies, to which it belongs, is not venomous. 
^dly, That a thin and acute tail is by no means to be confi- 
dered as peculiar to venomous Serpents ; though a thick and 
obtufe one is only to be found among thofe which are not 
venomous. 
The Anguis ventralis of Linnjeus,. is fo very- like the Lacerta apoda, 
defcribed by Pallas, in Vol. XIX. of the Novi Comment, Petrop. as to render 
it doubtful whether it may not be the fame. When I firft examined it, I 
conlidered it as a Lacerta, on account of the projecting future along the body, 
and the open ears ; but I have fince met with a fpecimen which had two large 
echinated Penes (as they are called) a charadter which is, I believe, peculiar 
to Serpents. 
4thij 3 , 
