Fig. 133.–Phrynosoma cornutum ("Horned Toad"). × 1.
Ph. coronatum, an inhabitant of California, has an additional smaller spine between the two large occipitals. The scales of the belly are quite smooth.
These peculiar-looking and interesting creatures recall some of the extinct Dinosaurs in the curious configuration of their head: small miniatures indeed. In order to be kept in good health, and to be observed properly, they require, above all, warmth, sunshine to bask in, sand to burrow in, and proper food. The latter consists of all kinds of small insects, the necessary variety of which is best procured by making sweepings with a butterfly-net in a meadow. They take green-flies, house-flies, ants, smooth caterpillars, small moths, meal-worms, wood-lice, etc. The food is snapped up very quickly by a flash of the tongue, which can be turned out, almost like that of a frog, but only to the extent of half an inch. Water in the shape of dew, or drops, is absolutely necessary. When in good condition, they defaecate regularly every alternate day.
Fig. 134.–Phrynosoma coronatum ("Horned Toad"). × 1.
They love to bask in the broiling sun, heating themselves well through; and in the afternoon, long before sunset, when the sand is warmed up to 40° C., or fever-heat, they prepare to go to bed. For this they select a dry and soft spot, and within a few minutes manage to dig themselves in flat, literally sinking into the sand by pushing themselves forwards, and by shovelling the sand upon their backs with peculiar motions of the fringed sides of their flat bodies. Sometimes the spines of the head remain sticking out, looking like dry thorns scattered over the sand. To prevent the latter from getting into the nostrils, these are provided with closely-fitting valves. Thus they remain concealed during the night, and not until the sun is well up do they leave their hiding-place, first peeping out, and then raising their head and neck, letting the sand roll off between the spines. Still half concealed, the back covered with little pebbles, seeds, or bits of dry leaves, they wait for a long time before they feel lively enough to sally forth. Although mostly slow and deliberate in their movements, stalking about with arched back, and raised upon the fore-limbs, they can run fast enough for a few yards before they stop again and nod in a ridiculous way. When they see themselves observed, they shut their eyes and slowly sink down. On cool and dull days they do not appear at all, and during part of the cooler season they require artificial heat until they are ready to hibernate. Unless they are allowed to hibernate, they will keep on feeding through the winter, but in that case are sure to die in the following spring.
Fam. 3. Xenosauridae, with Xenosaurus grandis in Southern Mexico as the sole species, seems to connect the Iguanidae with the Anguidae. According to Boulenger, its affinity to the former is shown by the T-shaped interclavicle, the absence of symmetrical bony shields on the head and of osteodermal plates on the body. Affinity to the Anguidae is indicated first by the short tongue, which has a narrow, feebly incised, retractile anterior part, covered with flat papillae; secondly, by the teeth, which, instead of being hollow at the base, are solid; lastly, by the palatine bones, which are widely separated.
X. grandis, scarcely one foot in length. The body is depressed, covered above with minute granules and tubercles, below with smooth scales. A distinct fold of skin extends from the axilla to the groin, recalling the more strongly developed lateral fold of some of the Anguidae.
Fam. 4. Zonuridae.–This family, comprising four genera with about one dozen species in South and Tropical Africa, and in Madagascar, likewise seems to connect Iguanidae and Anguidae. It is distinguished from the former by dermal ossifications, which roof over the supratemporal fossa; from the latter by the tongue, the hollow teeth, and, in Zonurus at least, by the occurrence of dermal ossifications on the trunk and tail. The tongue is short, villose, scarcely protractile, entire, or but feebly nicked at the tip. The Zonuridae may therefore be defined as pleurodont African lizards with a short tongue, and with a bony roof to the supratemporal fossae.