The Order LACERTILIA includes only a single venomous species, which belongs to the family _Lacertidæ_, and is known as the _Heloderm_ (_Heloderma horridum_, fig. 124). It is a kind of large lizard, with the head and body covered with small yellow tubercles on a chestnut-brown ground. It sometimes exceeds a metre in length, and its habitat is confined to the warm belt extending from the western slope of the Cordilleras of the Andes to the Pacific. It is met with especially in the vicinity of Tehuantepec, where it inspires the natives with very great dread. It is a slow-moving animal, and lives in dry places on the edges of woods. Its body exhales a strong, nauseous odour; when it is irritated, there escapes from its jaws a whitish, sticky slime, secreted by its highly developed salivary glands. Its food consists of small animals. Its bite is popularly supposed to be extremely noxious, but, as a rule, the wound, though painful at first, heals rapidly. Sumichrast caused a fowl to be bitten in the wing by a young individual, which had not taken any food for a long time. After a few minutes the parts adjacent to the wound assumed a violet hue; the bird’s feathers were ruffled; a convulsive trembling seized its entire body, and it soon sank to the ground. At the end of about half an hour it lay stretched out as though dead, and from its half-open beak there flowed a sanguinolent saliva. There was no movement to give any sign of life, except that from time to time a slight shiver passed through the hinder part of its body. After two hours, life seemed gradually to return, and the bird picked itself up and crouched on the ground, without, however, standing upright, and still keeping its eyes closed. It remained thus for nearly twelve hours, at the end of which time it once more collapsed, and expired. [Illustration: FIG. 124.--_Heloderma horridum._] A large cat which Sumichrast caused to be bitten in the hind leg did not die, but immediately after being bitten the leg swelled considerably, and for several hours the cat continued to mew in a way that showed that it was suffering acute pain. It was unable to stand, and remained stretched out on the same spot for a whole day, unable to get up, and completely stupefied.