Rhampholeon, of tropical continental Africa, with several species, is likewise remarkable for the stunted and dwarfed appearance, and for the peculiar claws, each of which is furnished with a second cusp which is directed downwards. The tail is much shorter than the body. The total length of Rh. spectrum of the Camaroons is about 3 inches.
CHAPTER XIII
SAURIA, continued–OPHIDIA–SNAKES
Order II. OPHIDIA–SNAKES.
Saurians which have the right and left halves of the lower jaw connected by an elastic band.
The Snakes are the most highly specialised branch of the Sauria, from which they do not differ in any fundamental characters. The chief modifications consist in the absence of the limbs and limb-girdles (a feature intimately correlated with the much-elongated body), and in the swallowing apparatus. The reduction of the limbs and the elongation of the body also occurs in many Lacertilia; in several of the older families of Snakes (e.g. Typhlopidae and Boidae) vestiges of the hind-limbs and even of the pelvis are still in existence. Even the peculiar suspensorial apparatus of the lower jaw approaches that of the Lacertilia in the burrowing Ilysiidae and in Xenopeltis.
In the majority of the Snakes the quadrate is very loosely suspended from the squamosal (by some authorities homologised with the supratemporal bone of other reptiles), and this again is loosely attached to the lateral parietal region of the skull, placed horizontally, and elongated so far backwards that the vertically placed quadrate lies in a plane behind the skull. In most Snakes the elongated pterygoids are loosely attached to the inner side of the distal end of the quadrates, and they also often touch the mandibles. The whole palatal apparatus is movably attached to the skull, except in some burrowing families. The right and left pterygoids and palatines are widely separated from each other. The pterygoids and maxillaries, connected by the ectopterygoids, are absent, owing to reduction, in the Typhlopidae and Glauconiidae only. The premaxilla is unpaired and small, and is rarely furnished with teeth. The latter are always sharp and recurved, and are lodged in sockets upon the edge of the supporting bone, with which they become firmly ankylosed. There is a perpetual succession of teeth. In the majority of Snakes teeth are carried by the maxillaries, palatines, pterygoids, and dentaries, rarely by the premaxillaries. The palatal teeth are restricted to the palatines in Oligodon, Dasypeltis, and Atractaspis only.
Peculiar modifications prevail in the poisonous Snakes. Those maxillary teeth which are at their base in connexion with the openings of poison-glands (modified upper labial glands), either have a furrow on the anterior side (Proteroglypha if the anterior teeth are grooved, e.g. the Cobras; Opisthoglypha if some of the posterior teeth are grooved), or the groove is converted into a canal, as in the Solenoglypha or Viperidae. The special modification of the maxillaries of the vipers with their long poison-fangs is described on pp. [587] and [637].
The orbit is generally closed behind by the postfrontal. Quadrato-jugal, postfronto-squamosal, and other arches are absent, so that the temporal fossa is quite open (see Fig. 156, p. [597], and Fig. 155, p. [596]). The occipital condyle is distinctly triple. The mandibles are composed of several bones, but the coronoid is absent in the Xenopeltidae, Colubridae, Amblycephalidae, and Viperidae; it is large in the Boidae, reduced to a nodule in the Ilysiidae.
The parietals are always fused into a large unpaired bone, which generally forms a sharp crest and partly overlaps the occipitals; there is no interparietal or pineal foramen.