ALLIGATOR LIZARDS. Genus Gerrhonotus⁴¹

Field characters.—Size large for a lizard, up to 12 inches, legs small; head large and diamond shaped; iris light yellow; body covered above and on sides with keeled scales in 14 or 16 lengthwise rows (pl. 58b, c, d); a flexible fold of skin, covered with granules, along each side of body; scales on under surface smooth and in rows lengthwise and crosswise. Coloration above, dark grayish, greenish, or brownish, with or without dark cross-bands. Under surface bluish gray. Movements slow; wriggles along clumsily, with much sidewise bending of body.

Occurrence.—Moderately common on west slope of Sierra Nevada from Upper Sonoran Zone (webbii) to lower part of Hudsonian Zone (palmeri). Recorded from Pleasant Valley eastward to Tuolumne Meadows.⁴¹ Lives on ground under chaparral and forest cover.

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⁴¹Two distinct species of Alligator Lizards live in the Yosemite region. They are similar to one another in general appearance, and little or nothing concerning possible differences in their habits is known. For these reasons they are here treated together.

SAN DIEGO ALLIGATOR LIZARD, Gerrhonotus scincicauda webbii Baird, a southern form which ranges north along the western flank of the Sierra Nevada, is found in the western part of the Yosemite region from Pleasant Valley eastward to Smith Creek (6 miles east of Coulterville) and to the western part of the floor of Yosemite Valley, at the foot of Rocky Point. It is characterized by having the scales on the back in 14 lengthwise rows and the scales on the side of the head behind the eye (temporal region) smooth. The general tone of color is brown or grayish brown, with about 10 well marked dark bands across the back. (See pl. 58b.)

SIERRA ALLIGATOR LIZARD, Gerrhonotus palmeri Stejneger, the species which is found in the higher portions of the Sierra Nevada (Canadian Zone chiefly), was recorded locally from Chinquapin, Merced Grove Big Trees, and the eastern part of the floor of Yosemite Valley (from the village) eastward to Tuolumne Meadows, and near Merced Lake. The scales on the back and sides are in 16 longitudinal rows and those of the temporal region are faintly keeled. The general tone of color is olive, not banded, but with ill-defined dark markings, and with sharp points of white along the sides. (See pl. 58c, d.)

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People often mistakenly attribute poisonous qualities to any unusual or formidable-looking animal, particularly if it be a reptile, and this is eminently true in the case of the Alligator Lizards. These lizards often attain considerable size, their heads are of the diamond shape popularly thought to be indicative of poisonous properties, and the temper of the animals is such that when handled they usually make an effort to bite. But the damage which one of these lizards can inflict on a person is usually limited to a sharp pinch from the strongly muscled jaws, without drawing blood. There are no poison glands whatever in this or any other of our California lizards.

The Alligator Lizard gains its popular name from the resemblance which the animal bears to the alligator, both in appearance and supposed temperament. The head is a prominent feature (pl. 58b) and gains in prominence as the individual increases in age, being no wider than the body in young animals but decidedly wider in old adults. The tail is long and slender and when unbroken is nearly twice the length of the head and body. This member is easily broken off, as it is in the cases of swifts and whip-tailed lizards; in the present species it readily grows out again, sometimes to nearly its original form and size, its regeneration here being, as a rule, more nearly perfect than it is in some of the other species of lizards. (See pl. 58b, d.) The fold of skin along the side of the body serves as a sort of expansion joint which can be opened out when the animal is puffed up, when it is excited, or when it is filled with food.

Both in the foothill country and in the high mountains the Alligator Lizards live on the ground, on chaparral- and tree-covered hillsides. Sometimes an individual is to be found in the edge of grassland, but the species does not go far out into the open. The legs and feet are small and weak.

When traveling, even when undisturbed, an Alligator Lizard progresses slowly and rather clumsily, wriggling its body from side to side. Some of the relatives of this lizard in other parts of the world have entirely lost their legs, and their locomotion is accomplished in much the same manner as in snakes. Perhaps this relative handicap on the part of the Alligator Lizard when making its escape or when cornered is compensated for by the formidable appearance and 'vicious' temper of the animal. The tongue is rapidly protruded, in the fashion of some snakes, and this, with the further feature of yellow iris, adds to the menacing 'front' put up by the animal.

The Alligator Lizards (both species) are insect feeders.