HTSTORY OF OPHIOLOOT. 
115 
extended, allowing themselves to be guided by the same 
principles, and are hence unable to follow a natural system. 
We shall see in the sequel to what errors this manner of 
viewing the subject has given rise, and on what a false path 
it has conducted. 
Klein,* most frequently guided in his labours by a spi- 
rit of contradiction, has arranged among serpents many 
Annelides, and even Intestinal Worms. The true serpents 
are by him divided into two classes, characterized by the 
form of the head and of the tail : those with the head of 
the same diameter with the body, and with a short and 
rounded tail, form his genera Amphisbsena and Scytale ; 
the other class comprehends the Kynodons or venomous 
snakes, in which he distinguishes the Viper, the Naja, and 
the Crotalus ; the innocuous serpents are lastly distributed 
into the genera Ichthyodon, Lytaidon, and Anodon, estab* 
lished on the form of the teeth. 
It is obvious that this author is the first who has pro- 
posed to separate the venomous from the innocuous serpents. 
It was afterwards that Gray! especially devoted himself 
to discover the marks by which to characterize these two 
divisions. The result of his researches is, that there is no 
other method of recognising the venomous species, but by 
ascertaining the presence of the fangs. This memoir con- 
tains many good observations on the dentary system of 
serpents. 
The great reputation that Laurenti acquired by the 
publication of his synopsis J is not less than his merits as 
a systematic author. His third order of Eeptiles compre- 
hends the serpents, which he distributes into the genera 
Chalcides, Csecilia, Arnphisbsena, Anguis, Natrix, Cerastes, 
Coronella, Boa, Dipsas, Naja, Caudisona, Coluber, Vipera, 
Cobra, Aspis, Constrictor, and Laticauda. The numerous 
species with which he has enriched his scheme, being, for 
the most part, established and characterized on the figures 
of Seba, are chiefly nominal, as may be seen in analyzing 
^ Tentamen HerpetologicBi Konigshergi^ 1755. 
t PMl. Trans, ^ Ixxix., pi. p. 21. 
t Synopsis Beptilium, Vienna, 1768. 
