2466 



SCALED REPTILES 



collar bones are present; and when the limbs are absent, some traces of the bones 

 forming what is known as the shoulder girdle persist. In form the tongue is flat- 

 tened, and, as already said, cannot be withdrawn into a basal sheath, although such 

 a sheath may be present. In most of the members of the suborder the upper sur- 

 face of the body is clothed with the overlapping scales characteristic of the order in 

 general, these scales being in some cases underlain by bony plates; but in most 

 geckoes the upper scales are granular, although sometimes juxtaposed. 



Numerically, lizards are by far the most abundant of all reptiles at 

 Numbers and t jj e p resen t day, the total number of species not falling far, if at all, 

 short of one thousand seven hundred, which are arranged under 

 twenty distinct families. In this abundance at the present day, 

 coupled with the specialized features of the greater part of their organization, liz- 

 ards may be regarded as occupying a very similar position in the reptilian class to 

 that held by the perching birds in the preceding class. With the exception of the 

 polar and subpolar zones, lizards are distributed over the whole globe, ranging in 

 some districts from the level of the sea to the limits of eternal snow, and found 



Distribu- 

 tion 



SKELETON OF UZARD. 



alike in fruitful and barren districts, in the neighborhood of water, and in the most 

 arid deserts. Whereas, however, in the colder regions they are poor in species and 

 small in size, it is in the tropics and subtropical regions that they attain their maxi- 

 mum development, as regards numbers, bodily size, richness of coloration, and 

 peculiarity of form. 



As regards their distribution over the surface of the globe, lizards present a 

 most remarkable difference from what obtains among Amphibians (frogs, newts, 

 etc.), and, to a less degree, among tortoises. For instance, whereas Amphibians, 

 and to some extent tortoises, have their distributional areas defined equatorially, 

 such lines of division, in the case of the present group, must be drawn meridio- 

 nally. Thus, in the case of Amphibians, one great distributional province includes 

 Europe, Asia, and North America, and the second embraces the regions lying south 

 of the Equator; whereas in the case of lizards one area marked by peculiar forms 

 will include the Old World and Australia, and the other will comprise the whole of 



