CHAPTER IY. 
Scaled Reptiles—Lizards and Chameleons,— Order Squamata ; 
Suborders Lacertilia and Rhiptoglossa. 
Although in popular language the term lizard is applied to any four-legged reptile, 
exclusive of turtles and crocodiles, in scientific usage it is more convenient to restrict 
it to those members of the great group of scaled reptiles which do not come under 
the designation of either chameeleons or serpents, whether they are provided with 
legs, or whether they lack those useful appendages. Formerly, indeed, lizards and 
chamseleons were regarded as constituting an order by themselves cpiite apart from 
serpents, but the two groups are now known to be so intimately connected as to 
render any such division inadmissible; and they are accordingly here placed in a 
single order, known as scaled reptiles, or, technically, Squamata. Structurally, this 
ordinal group differs very widely indeed from any of those hitherto treated, and as 
it is essential to gain a correct idea of such structural differences, they may first be 
taken into consideration. 
Skull Taking their name from the coat of overlapping horny scales 
with which they are generally invested, the scaled reptiles' are 
primarily distinguished from all the foregoing groups by the circumstance that the 
quadrate-bone is more or less movably articulated to the skull, and has its lower 
end projecting freely therefrom, instead of being immov¬ 
ably wedged in among the other bones. To this primary 
point of distinction it may be added that the lower 
temporal arch of the skull is wanting, so that there is 
no bony bar connecting the lower end of the quadrate- 
bone with the upper jaw, as there is in the crocodiles; 
the absence of this bar being well shown in the figure of 
a lizard’s skeleton. Then, again, the palate, instead of 
being more or less completely roofed over by bone, is 
largely open, its bones taking the form of long bars. 
In some lizards, as in the one of which the skeleton 
is figured, the upper surface of the skull is covered 
by bone, so that the temporal fossae are roofed 
over. 
Ribs and Another important feature of the order is to be found in the 
vertebrae. circumstance that the ribs in the region of the back are single-headed, 
and are articulated to the backbone by means of a facet ( d ) situated on the body 
of each vertebra. This feature at once distinguishes the order from the crocodiles 
and dinosaurs, in which the ribs are two-headed, and in the back articulate to a 
