REPTILLIA. O75 
have indications of a posterior pair of extremities, in the form of scaly, un- 
divided appendages, one on each side of the anus. The single species is 
known in Russia as the sheltopusik. The genus Chalcides, whose species are 
mainly South American, has both pairs of extremities, but in a rudimentary 
state. The anterior pair terminates in three or four scaly tubercles, while the 
posterior is represented by two slender spines. By the absence of an external 
auditory cavity, it is distinguished from Chama@saurus, in which none of the 
rudimentary extremities exhibit any subdivision. The genus Sauwrophis in- 
troduces us to the species having more highly developed extremities. Here 
each foot has four toes. The single species known, S. ¢etradactyla (pl. 74, 
fig. 67), inhabits the southern portions of Africa. The remaining genera 
have five toes on each foot; the most interesting of these is the genus 
Gerrhonotus, which, represented by eight species, inhabits Mexico and 
California. 
The second sub-family, that of the Glyptodermes, corresponds very nearly 
to the family Amphisbzenide of some authors. Here the body is entirely 
deprived of scales, in place of which the skin is divided by circular and longi- 
tudinal furrows into small quadrilateral compartments, sometimes variously 
colored, and then resembling mosaic work. ‘These subdivisions are generally 
slightly tubercular and projecting. ‘There are faint indications of the lateral 
furrow of the more typical Chaleidide. Most of the species bear a striking 
resemblance to the Ophidia, with which they have usually been classed ; 
they may, however, be distinguished by the entirely saurian skull, with the 
symphisis of the two halves of the lower jaw; by the saurian tongue; 
and by the fact that the vertebrae are united by fibro-cartilage. In one 
sof the ophioid genera, Trogonophis, the teeth are acrodont, or attached 
on the cutting edge of the jaws, while in all the rest they are pleurodont, 
or applied along the inner edge. The genus Amphisbena, or double 
walkers, are so called from the close resemblance between the anterior 
and posterior extremities of the membranous body. They appear as if 
possessing a head at each end, and are hence supposed to be capable of pro- 
gression in either direction. They are often found in the nest of the termites, 
where they feed upon the young ants. The genus Chirotes presents the 
remarkable anomaly among saurians of having two fore feet, each with five 
fingers. In the absence of hind feet, the anterior being present, we see 
a strong resemblance to the batrachian genus Siren. ‘The presence of a 
sternum further distinguishes Chirotes from Amphisbena. ‘The single 
species, Chirotes canaliculatus, is found in various parts of Mexico, 
extending northwards along the eastern base of the Rocky Moun- 
tains. 
Fam. 3. Lacertida. Species of this family have a cylindrical elongated 
body, with the tail sometimes of very great length, and always well developed. 
The feet are four in number, with four or five distinct toes of unequal 
length, all provided with curved claws. The head is in the shape of a 
truncated four-sided pyramid, depressed, and covered with polygonal sym- 
metrical plates. The typanum is distinct, sometimes externally apparent. 
Eyes usually with three movable eyelids. The mouth is deeply cleft, and 
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