Say on Herpetology. 261 
fear. In my anxiety to secure him, he eluded my grasp, and 
by asudden and rapid exertion, disappeared, with all the rapid- 
ity of movement so remarkable in the constrictor. This last, 
from his celerity, is known in many districts by the name of 
er. 
- Coluber heterodon. This viperine species, of which Latreille 
has formed a genus under the name of Heterodon, varies con- 
siderably in its markings, and like most of our serpents, is not 
constant in the number of its plates and scales, (126, 48— 
138, 42—141, 42, &c.) perhaps too much reliance has been 
Placed upon color, and upon the number of the plates and 
scales beneath the body, of the Ophidiew generally. In the 
form of the anterior termination of the head, the heterodon, is 
remarkable, and a good specific character may be obtained 
from the orbital scales, which are eleven or twelve in number ; 
the parabolic curve which passes through the eyes, and ter- 
~ Minates at the maxillary angles, is also generally present. This 
same serpent was figured in Deterville’s ed. of Buffon, under 
the name of Colewore cannelee. The heterodon abounds in 
Many sandy situations, and near the sea shore. Several per- 
Sons pursuing a pathway, passed within a few inches of one of 
them without his betraying any emotion, but the moment he 
Perceived me advancing with my eye fixed upon him, he with 
@ sudden exertion assumed a defensive attitude, by elevating 
the anterior portion of his body, flattening his head, and 3 or 
