XX INTRODUCTION. 
ONYCHOPHIDIA. 
Serpents of the second suborder, Onychophidia, are distinguished by rudi- 
mentary posterior limbs, the only external evidence of which is a small 
claw or prominence on each side of the vent. This group contains the 
largest of the snakes, the Boas and Anacondas of the Americas and the 
incubating Pythons of the old world, species of which are said to reach 
a length greater than thirty feet. The section of the group containing 
species with thick non-prehensile tails is represented in California and 
Mexico by several burrowing snakes belonging to the genus Charina ot 
the Erycide. Eunectes, containing the Anacondas, is a South American 
genus, and its species reach greater size than other new world snakes; it 
belongs to the section with prehensile tails. Of this section there are three 
species of Boa in Mexico; a doubtful fourth is reported in the Yellow Boa, 
Chilabothrus inornatus, properly of the West Indies. These Onychophidia 
are expert climbers, and many are equally active in the water. None of 
them are venomous. They are able to swallow animals of much greater 
diameter than their own. Ordinarily they seize the prey with the teeth 
and crush it in folds of the body. 
ACACOPHIDIA. 
The innocuous snakes comprise all the common, harmless species of the 
ground, fresh water, or trees. Being not at all harmful, and feeding on 
mice, moles, insects, ete., many of them are important aids in restraining 
the increase of the most destructive enemies of the husbandman. The 
vulgar fear of these animals is mainly the result of education or of preju- 
dice, which lacks foundation in facts. In reality, some of the most dreaded 
b] 
have no existence. Such as the “ Ring” or “Hoop Snake,” which is said 
to take the end of its tail in its mouth and roll over and over like a hoop, 
killing everything it touches with its venomous horn, and the “ Blow 
Snake,” the breath of which is deadly, are mere fictions. A few members 
of the division prey. upon others, and are said to conquer and eat species of 
the Toxicophidia. 
Several are possessed of considerable curiosity, and sometimes follow 
objects that have attracted their attention. The common black snake, 
Coluber constrictor, occasionally chases men in this way, but if turned upon 
at once seeks safety in flight. It happens at times that harmless species 
