36 
LECTURE VIL 
accidental violence. But poisonous Serpents may 
often be at least guessed at, though not demon- 
strated, from the liabit or general appearance of 
the animal, most of the venomous Serpents having 
rather large heads, covered with small scales, 
whereas those wdiich are innocent have the head 
generally covered with large scaly plates ; but on 
the other hand some highly venomous Serpents 
have the head covered with large scales also 3 so 
that no absolute mark of distinction can be found 
except the fangs. In general it may be said that 
innocent Serpents have four rows of teeth in the 
upper jaw j two on the palate and the rest on each 
side; but tliat poisonous Serpents have no other 
outward or side-teeth but the fangs. 
The genera or particular sets of Serpents esta- 
blished by some modern naturalists are pretty nu- 
merous, and even unnecessarily so. Linnaeus on 
the contrary established but few. His first genus 
is that of Ci'otalus or Rattle Snake. Its character 
is that beneath the body are broad scaly semi- 
circular transverse plates or shields ; the same, to- 
gether with some divided shields beneath the tail, 
and the tail itself terminated by a rattle, composed 
of many dry horny flattish organs of a peculiar 
