In other series of Scinks, the distinctions of which are far from being conspicuous, we again have limbless genera, or nearly so, as the Australian Soridia lineata, which has one pair of small, posterior, undivided extremities; while in another Australian form, the Rhodona punctata, the anterior pair of limbs are simple and undivided, while the hinder divide into two unequal toes, and the two pairs of limbs are situate as distantly apart. And thus we may continue to trace the successive gradations, in sundry genera, until we arrive at the Scincus officinalis of North Africa, a well-known reptile, the geographical range of which extends eastward into Afghanistan, and which was formerly in considerable request for its supposed medicinal properties. Indeed, this notion still prevails in Hindustan, into which country dried specimens of both this reptile and of Sphenocephalus tridactylus (p. 101) are brought by Afghan traders, and are sold in the bazaars. Both of these are Sand Lizards, which burrow into the sand with great rapidity.
We now come to the Tropidophorinæ, or second sub-family of Scinks indicated by Dr. Gray (vide [p. 102]), which have always well-developed limbs, the body only moderately elongated, and the scales variously keeled. Several species of larger size appertain to this series, as the Cyclodus gigas of Australia, and the curious Stump-tail Lizards, Trachydosaurus rugosus and T. asper, of the same insular continent, which latter have most prominently rugous scales, and the tail literally appearing like the short and abrupt stump of one. Egernia Cunninghami and Tropidolesma (of different species) are other comparatively large Australian Lizards; and examples of most of those that have been mentioned may generally be seen alive in the London Zoological Gardens, where the Cyclodus gigas has bred and proves to be viviparous. Of the species of Euprepes, of which several inhabit the Indian region, some (as the very common E. rufescens) are viviparous, and others (as E. multicarinata) are oviparous. These have three more distinct, though not prominent, keels upon each scale; and the different species inhabit both the Old World and the New, as well as Australia. The Galliwasps (Celestus) of the West Indies, and sundry other genera, do not greatly differ. Of Tropidophorus, which has exceedingly rugged scales, the species inhabit the Indo-Chinese countries, and one (T. cocinsinensis) is found likewise in the Philippines; while of another (T. Berdmorei), in Burmah, Mr. Theobald remarks that "its scales are dull and lustreless, and the coloration peculiar for a Scink. It harbours under half-immersed stones, and enters the water and gravel freely." In several of this family of Lizards the scales are beautifully iridescent, and many of them show longitudinal pale or white lines, or are otherwise variegated.
Nearly akin to the extensive family of Scincidæ, there are three small families (as classed by Dr. Gray), the species of which are peculiar to Australia. They have small, undivided, posterior limbs only, or are quite limbless. These families are the Lialisidæ, founded on three or more species of a single genus, Lialis; the Aprasiadæ, founded upon one species only—Aprasia pulchella, which is limbless; and the Pygopodidæ, comprising the two genera Pygopus and Delma, the former containing two, the latter only one ascertained species. The Gymnopthalmidæ constitute still another small family, quadrupedal, but with the limbs small and weak. Of seven genera referred to it, five are Australian, one is European, and one belongs to South America. Ablepharus pannonicus is a small Lizard of this family, inhabiting Eastern Europe, with a congener, A. bivittatus, in the Caucasus; and Gymnopthalmus lineatus inhabits Brazil and the Island of Martinique.
In the second tribe of Leptoglossa, entitled Cyclosaura, the scales of the belly are square, in cross bands; those of the back and tail are rhombic and imbricate, or circular and subgranular; the tongue is lengthened, and more or less conspicuously furcate; and the eyes are diurnal, having two valvular lids. The limbs are generally well developed; but in several genera they still are more or less rudimentary, or even absent.
There are four small families in which the sides are rounded and covered with scales like the back. Of these, that of Chamæsauridae is founded upon the South African Lacerta anguina of Linnæus, now Chamæsaura anguina, which has the limbs quite rudimentary. In the American families of Cercosauridæ, Chirocolidæ, and Anadiadæ, the limbs are moderately developed, and have each five toes. The two last-mentioned families are founded each upon a single species, Chirocolus imbricatus and Anadia ocellata; and the other contains the two genera Circosaura and Lepisoma—of which the first comprises some two or three species only. All of these reptiles have exceedingly long tails, though not so inordinately long as in the Lacertidæ of the genus Tachydromus.
Certain other families have a distinct longitudinal fold, covered with small granular scales on each side. These are the families Chalcidæ, Holaspidæ, and the more extensive one of Zonuridæ. The Chalcidæ have the head covered with regular many-sided shields, and the lateral fold is indistinct; limbs small and rudimentary, and the hind feet are undivided in the genera Chalcis and Bachia, with three tubercles in place of toes in Microdactylus, and with four clawed toes in Brachypus. Each of these genera is founded on a single species, and all are doubtless peculiar to the New World. The Holaspidæ is also founded on one species only, the Holaspis Guentheri, which again is supposed to be South American. It has four well-developed limbs, a double row of plates along the back and upper surface of the tail, and the latter organ is curiously serrated laterally.
The Zonuridæ constitute a considerable family, to which some eighteen or twenty genera are assigned, and which present considerable modification of form. The ears are distinct, whereas in the Chalcidæ they are hidden under the skin. The head is pyramidal, or depressed, and covered with regular many-sided shields; eyes with two valvular lids. Limbs mostly well developed, but short in some, and rudimentary, or even wanting in the so-called "Glass-snakes" which constitute the sub-family Pseudopodinæ. There is no external trace of them in the North American Glass-snake, Ophisaurus ventralis; and in the Old World genus, Pseudopus, there is only one pair, posterior, rudimentary, and undivided. These reptiles are long, and serpentiform in shape: whilst in other Saurians the whole skin of the belly and of the sides is extensible, the extensibility is limited in the "Glass-snakes" to a separate part of the skin; and, as Dr. Günther remarks, "the scaly covering of the upper and lower parts is so tight that it does not admit of the same extension as in Snakes and other Lizards; and the Pseudopus, therefore, could not receive the same quantity of food in its stomach as those animals, were it not for the expansible fold of the skin running along each side of its trunk." One species of Pseudopus, the P. Pallasii, inhabits Asia Minor and the south-east of Europe; and there is another, P. gracilis, in the Indo-Chinese countries (or those lying eastward of the Bay of Bengal). A second sub-family, Gerrhonotinæ, is peculiar to America, and consists of more ordinarily-shaped Lizards, which are ranged in four genera. Together with the Ophisaurus, or American Glass-snake, they are the only known Zonuridæ that inhabit the New World. The great mass of this family and all of its most characteristic species are African, and these are arranged by Dr. Gray under the sub-families Cicigninæ and Zonurinæ. In the first of these sub-families the tail is smooth, or unarmed, and in the second it is spinous. The Cordules, Cordylus, Zonurus, &c., are very characteristic Lizards chiefly of Southern Africa, several species of which have been figured by Sir Andrew Smith. They are mostly of shortish form, and the neck is more or less spinous; the body-scales in some (as Zonurus cataphractus) being extraordinarily rugous. These Lizards squeeze themselves into crevices in the rocks, in which they hold on so firmly by their nuchal spines that it is next to impossible to dislodge them, the tail commonly giving way at once if it be attempted to pull them forth by means of it.
The family of Lacertidæ, comprising our ordinary European Lizards, have no longitudinal fold along the sides, but generally one across the throat; the tail is very long, rounded, with its scales arranged in rings, being also fragile; the head is covered with shields, which are symmetrically arranged; scales on the back granular or rhombic; on the sides granular; on the belly largely quadrangular or rounded, and arranged in cross-bands; eyes diurnal, with eyelids; the tympanum distinct; limbs always four, and well developed. This group of Lizards has no representative in America or (so far as known) in Australia.
The sub-family of Tachydrominæ is included by Dr. Gray in the family Zonuridæ. These are Asiatic Lizards, with a most inordinate length of tail, the fore and hind limbs being not placed distantly apart, as in the various anguiform Lizards already treated of—there is an indistinct collar, and the toes are not serrated or keeled. Two genera have been distinguished, Tachydromus and Tachysaurus, the latter founded on a Japanese Lizard, T. japonicus. At least three species are known of Tachydromus, two of which inhabit China, T. septentrionalis and T. meridionalis; the third belonging to the Indo-Chinese countries, T. sex-lineatus. In an example of the last, measuring fourteen inches long, the tail occupies eleven inches and a half. It is the longest-tailed creature that we have any knowledge of, in proportion to its other parts; indeed, something quite wonderful to behold and muse over.
The rest of the Lacertidæ are chiefly from Africa and the south of Europe; there are probably more of them to be discovered in Middle Asia, and only three or four species are known to inhabit the Indian region. Fifteen or more genera are recognised. In temperate Europe (inclusive of the British Islands) two species are common—the Zootica vivipara and the Lacerta agilis. The former, as its name imports, is viviparous, whereas the other genera belonging to the family are (so far as known) oviparous. Others occur in the south of Europe.]