(a) Ancistrodon.
(b) Lachesis.
The second group includes only those snakes the tails of which are terminated by the scaly appendage known as the “rattle.”
These are likewise divided into two genera:—
(c) Sistrurus.
(d) Crotalus.
(a) Ancistrodon.
Usually with 9 shields on the head, or internasals and præfrontals broken up into scales. Body cylindrical: scales smooth or keeled, with apical pits. Tail moderate or short; subcaudals single or in 2 rows.
Fig. 68.—Ancistrodon piscivorus (Water Viper). (After Stejneger.)