g6 ' Dr. Gray’s Oifervations , &c. 
In the Preface to the Mufeum Regis, and in the Intro- 
duftion to the clafs Amphibia, in theSyftenra Nature, Linnjeus 
fays, that the proportion of venomous Serpents to others, is 
i in 10 ; yet in the Syftema Naturae, in which the fum total 
of fpecies is one hundred and thirty-one, he has marked twenty- 
three as venomous, which is fomewhat more than i in 6. How 
lie came to be fo much at variance with himfelf, I know not; 
hut the laft mentioned proportion feems to me to be not far 
from the truth ; as I find that I have examined one hundred 
and fifty -four fpecies of Serpents, of which number twenty- fix 
appear to be venemous. 
I have already mentioned, that the Coluber ftolatus and the 
niycierizans, though marked by Linn aj us as venomous Ser- 
pents, certainly are not fo ; and that I fufpect the fame may 
be faid of the Leberis, and Dipfas. I have alfo obferved, that 
the Boa contortrix, Coluber Ceraftes, and laticaudatus, none of 
which are marked in the Syftema Naturae, are all of them 
venomous ; to thefe laft may be added the Coluber fulvus. 
If Linn^us’s fpecies were all accurately examined, I have 
no doubt but more errors, of both kinds, would be found ; for 
it muft be obferved, that though I have examined a greater 
number of fpecies than Linn^us, not above half that number 
are of thofe defcribed by him ; consequently there remains more 
than one-third of his fpecies which I have never feen. The 
number I have examined, however, feems to me fufficiently great 
to warrant the inferences I have drawn from that examination. 
That feme exceptions to them might be found, by the exami- 
nation of a greater number, is very poflible ; but, if thefe ob* 
fervations fhall tend to rectify the falfe notions which have 
been entertained refpe&ing venomous Serpents, and to render 
the diftimftion between them and others more clear, I truft 
they will be thought not totally ufelefs. 
