Animals called , , by Linnaeus, Amphibia . 25 
that which follows it, Coluber. In that genus are many 
venomous fpecies, and it is very certain that, in general, they 
have the fore-mentioned characters ; examples of which may 
be feen in the Atropos, Ceraftes *, atrox, Berus, and others. 
It is, however, equally certain, that there are fame in which 
they are not to be found. As an example of this, I need only 
mention the Naja, a fpecies well known to be very venomous ; 
the head of which is neither deprefled nor broad, is covered 
with large fcales, and is, in every refpect, a complete exception 
to what has been faid, refpefting the heads of venomous 
Serpents. 
Since then, there are venomous Serpents in which the 
fore-mentioned characters, viz . a broad and deprefled head, 
covered with fmall fcales, are not to be found ; I [hall next 
examine whether thofe characters are to be found in any of 
thofe Serpents which are not venomous. In the genus Coluber 
there are very few (except venomous ones) which have the 
head much broader than the neck ; and of thofe few, I believe* 
every one has the head covered with large fcales. But in the 
genus Boa, though no fpecies is venomous, except the con- 
tortrix, almofl: every one has the head broad, deprefled, and 
covered with fmall fcales. The canina, Conftrictor, hortu- 
la£a, befides fome others not defcribed by Linnaeus, furnifli 
\ ^ 
* The Ceraftes is not marked by Linnjeus as a venomous fpecies. He pro- 
yJbably depended upon Hasselcluist’s defcription, which I fufpeft to have been 
tfnade from a mutilated fpecimen. Mr. Ellis’s defcription in the Philofophical 
Tranfa6tions, Vol. LVI. p. 287. is only a Tranflation of Hasselquist’s. But 
he obferves, that Dr. Turnbull told him it was venomous. That it is fo, I 
have not the fmalleft doubt, though in the only fpecimen I have feen of it the 
fangs were wanting. Imperato, who has given a figure of it (Hift. Nat. p. 784. 
Ed. Nap.), fays it is very venomous, 
Vol. LXXIX. 
E 
examples 
