HATTERIA AND THE LIZARDS 
saurs, seem to have had smooth scaleless skins, but no 
living reptile is without this tesselated armature. The 
existing reptiles are to be divided into five orders, 
but their numbers to-day are much below their numbers 
in past times. The reptilia are clearly a waning race as 
a whole, though of the existing orders most are more 
numerous now than they ever have been so far as the 
geological evidence at our disposal enables as to say. 
As to their numbers to-day, Dr. Gadow asserts that 
there are about 3,500, so that there are more reptiles 
than mammals, but considerably fewer than there are 
fish and birds ; for of the latter we know some 10,000, 
and of fishes some 8,000, while there are something like 
2,700 mammals and. about 1,000 amphibians. The 
enormous majority of living reptiles belong to the 
groups of lizards, snakes, and tortoises. There are 
but few crocodiles, and Hatteria is the only living 
example of its own group. 
LIZARDS : THE ORDER LACERTILIA 
The only other reptiles with which the lizards could 
be possibly confounded are the crocodiles, snakes, and 
the New Zealand Hatteria, which is the sole living 
representative of an otherwise extinct order, Rhyncho- 
cephalia. The turtles and tortoises are so distinct that 
there is no danger of confusion for the most ignorant 
of Natural History. From the crocodile tribe the 
lizards are to be distinguished by a variety of characters, 
which are, however, deep seated, and thus not easily 
appreciable to one examining the animals in a menagerie. 
As to purely external characters, it is most difficult 
to draw a line. In the crocodile tribe the nostrils are 
very plainly on the upper surface of the snout and 
protrude somewhat, which is of course in relation to 
the aquatic life of these creatures. The vent is a 
longitudinal orifice and not a transverse one as in 
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