BROOKESIA AND RHAMPHOLEON 
tailed monkeys of the New World and to the tailless or 
stumpy tailed forms among the monkeys of the Old 
World. But in the case of the chameleons all are Old 
World. Male and female chameleons often show exter- 
nal differences, some of which are quaint and exagger- 
ated. The common chameleon, which is African, and 
just extends into Europe and Asia Minor, shows the 
slightest difference of this kind ; in the male, the casque, 
as we may term the posterior projecting end of the head, 
is longer than in the female. Several species, appropri- 
ately named “ Calcarifer’”? and “ Calcaratus”’ on this 
very account, have a kind of spur on the hind legs just 
above the ankle, which spurs are again peculiar to the 
males. But the most extraordinary difference of the 
kind is to be seen in a few forms, of which a species found 
high up at an altitude of 6,000 feet on Mount Ruwenzori, 
in tropical Africa, forms an example. This chameleon, 
which was named after Sir Harry Johnston, presents us 
with three long horns upon the forehead, which give to 
this reptile a most truculent aspect. Another species 
from the same mountain has in front of the nose a for- 
wardly directed bony outgrowth. No chameleons are 
very large. Brookesia and Rhampholeon, just alluded 
to, are quite tiny, three inches or so. So, too, is the 
“dwarf chameleon,” a South African species, charac- 
terized by its green colour and by a patch on the side of 
a beautiful brick red. On the other hand, the giant of 
the tribe, Chameleon parsoni, is a couple of feet or so in 
length. 
Tue MONITOR OF THE NILE 
Varanus niloticus is the full-dress name of a large 
lizard whose habitat is indicated by its name, but which 
also strays into other parts of Africa. It is one of a 
genus of lizards entirely confined to the Old World, which 
has been variously termed Monitor, Varanus, Regena, 
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