Home › Volumes › Reptiles › Lizards
Keeled Lizard
Colouration.—Above, the colour is brown or olive, with numerous dark and wavy cross-bands, many of which are bordered with white spots. The soft strips of skin on the sides are much like the general ground colour and usually contain rounded patches of white. The abdomen is greenish-white.
Dimensions.—Following are the measurements of a specimen of average size, from California:
Distribution.—This is the only species of the genus that is widely distributed north of Mexico. It occurs throughout the Pacific Coast region from British Columbia southward to Lower California--inclusive. It ranges eastward into Texas, thence into Mexico and Central America.
Habits.—As the species of this genus appeal closely to one another in habits, these may be generally summed up under the head of the present reptile. The different species inhabit a variety of country, being found in forests, rocky situations and belts of chapparal. They are frequently found at an elevation of from 7,000 to 9,000 feet.
Slender in form, with very long and gradually tapering tail. The scales of the upper surfaces are very strongly keeled, particularly on the back and top of the tail. The scales of the abdomen are oblong in shape and highly polished; they are arranged in the same ring-like formation as those above.
Total Length . . . . . 11 3/4 inches.
Length of Tail . . . . . 7 1/2 inches.
Greatest Diameter . . . . . 3/4 inches.
Width of Head . . . . . 5/8 inches.
Length of Head . . . . . 1 in. (to behind ear.)
Length of Hind Limb . . . . . 1 3/8 inches.
Length of Front Limb . . . . . 1 1/16 inches.
The largest specimen examined furnished the dimensions given below:
Total Length . . . . . 15 1/4 inches.
Greatest Diameter . . . . . 1 inches.
Width of Head . . . . . 3/4 inches.
Synonyms.--The following technical names have been applied to this species: G. caeruleus, G. burnetti, G. wiegmannii, G. scincicauda, G. principis, G. grandis, and others that have appealed to alleged sub-species or varieties.
These lizards are less agile in their movements than other lacertilians of their size--such as the swifts and skinks--though they are by no means sluggish. However, they are more easily captured than the majority of their kind. While progressing leisurely over rough places, they are often quite snake-like in actions, the slender body and long tail following the outlines of the declivities, and, although the small limbs are constantly in use, the effect resembles a gliding movement. Such actions demonstrate the close relationship of these lizards to the serpent-like--limbless species.
All of the species of Gerrhonotus are provided with a well-developed and thick tongue, forked at the tip. When progressing--if not frightened, and hurriedly seeking shelter--the tongue is frequently protruded, generally to touch lightly the surface over which the creature crawls. After eating, the lizard employs the tongue vigorously to wipe the lips, and even though the prey be a small beetle, that has been swallowed practically entire, the same elaborate proceedings follows. The food consists mostly of insects, such as grubs, and the slower-crawling kinds. Captive specimens are very fond of mealworms. Occasional specimens are cannibalistic, devouring small lizards of other species, that may be placed in their cage.
The Plated Lizards evince the habit of parting with their tails upon the slightest provocation. Captive specimens with perfect tails are rather in the minority. Although many lizards will suddenly part with the tail by twisting themselves from one's grasp and leave the greater part of the caudal appendage writhing violently, to engross the enemy's attention, while the creature scampers off, the species of the present genus appear to be able to discard the tail voluntarily by a sudden throw of the appendage, as they are pursued and running for shelter. The abandoned tail twists, wriggles and undergoes such lively movements that if cast off in dried leaves or grass would cause enough commotion to cause the pursuer to stop and investigate it. Thus the tail may be said to play the part of a decoy in retarding the progress of the enemy. At the part where it has broken from the base, the cast-off portion looks remarkable, as it displays protruding, swollen filaments of flesh, these spreading from the member like the petals of a flower. If the lizard be examined, the stump of the tail will be found to contain cavities to represent these protuberances.
One might be led to imagine that the broken portions of the tail could be fitted together, but close investigation will show that the petal-like filaments are swollen in proportion to their original bases as is a champagne cork to the mouth of the bottle. The operation of shedding the tail is a bloodless one. Some weeks after the tail has been lost, a new member starts to grow slowly, appearing in abrupt, pointed fashion from the thick base of the original member. (Illustrated.) The new tail rarely attains more than half the length of the first appendage.