148 
LIZARDS. 
become perfectly rigid, in which state it easily breaks if bent or struck, thus giving 
origin to its Latin name. Generally frequenting woods, heaths, and commons, the 
blind-worm is one of the hardiest of British reptiles, making its appearance in the 
spring at an earlier date than any other kind. According to Bell, “ it retires in 
the autumn under masses of decayed wood or leaves, or into soft, dry soil, where it 
is covered with heath or brushwood, and penetrates to a considerable depth in such 
situations by means of its smooth, rounded muzzle and polished body.” It feeds 
chiefly upon slugs, supplemented by various insects and worms. In June or July 
the female produces from seven to twelve or thirteen living young, which are 
active almost immediately after birth, and soon learn to feed by themselves. Like 
other viviparous reptiles, the female is much given to basking in the sun during 
the period of pregnancy, in order that its heat may aid in developing the eggs 
contained in her body. 
The Poisonous Lizards. 
Family HELODERMA TIDJE. 
Two conspicuously coloured lizards, ranging from the isthmus of Tehuantepec 
in Central America as far north as New Mexico and Arizona, stand alone in the sub¬ 
order in being poisonous, their bite, in certain cases at least, being sufficiently severe 
to produce very serious symptoms even on human beings, while smaller animals 
are soon killed thereby. These two species are the Mexican poisonous lizard 
(Helodermct horridum ) of Western Mexico, and the Arizona poisonous lizard (H. 
suspectum) from New Mexico and Arizona; the former being known in its native 
country by the name of silatica. Nearly allied to the blind-worm, which they 
resemble in the general structure of their tongue and teeth, although distinguished 
by certain peculiarities in the conformation of the skull, and by the upper surface 
being covered with small granular tubercles, externally they are characterised by 
the depressed head, the plump, rounded body, the tolerably long cylindrical tail, 
the rather short limbs, in which the third and fourth toes are longer than the 
others, the exposed drum of the ear, and the transverse arrangement of the rows 
of tubercles on the upper surface. The curved and fang-like teeth are but loosely 
attached to the jaws, and have grooves in front and behind for the transmission 
of the poison; while there are also teeth on the palate. Beneath, the body and tail 
are covered with squared scales. In length, the figured species measures rather 
less than 20 inches, while the other is somewhat larger. The former has a yellowish 
or orange ground-colour, marked with a dark network on the head and body, and 
with blackish rings on the tail. Among the reddish sand, intermixed with dark 
pebbles, in which these lizards delight to nestle, this coloration, coupled with the 
granular nature of the skin, appears to be protective. 
Inhabiting dry regions from the western side of the Cordillera to the Pacific, 
and apparently never entering water, the poisonous lizards are nocturnal in their 
habits, lying during the day hidden among the vegetation in a listless state, and 
issuing forth at evening. Their movements are at all times deliberate; and as 
these lizards are most commonly met with in the wet season, being but seldom 
seen during the dry months from November to June, it is probable that they are 
