34 
SEXUAL SELECTION. 
Part II. 
There are other and much more remarkable dif- 
ferences between the sexes of certain lizards. The 
male of Ccratophora aspera bears on the extremity of 
his snout an appendage half as long as the head. It 
is cylindrical, covered with scales, flexible, and appa- 
rently capable of erection : in the female it is quite 
rudimental. In a second species of the same genus a 
terminal scale forms a minute horn on the summit 
of the flexible appendage ; and in a third species (C- 
Stocldartii, fig. 34 ) the whole appendage is converted 
into a horn, which is usually 
of a white colour, but as- 
sumes a purplish tint when 
the animal is excited. In 
the adult male of this latter 
species the horn is half an 
inch in length, but is of quite 
minute size in the female and 
in the young. These appen- 
dages, as Dr. Gunther has 
remarked to me, may be 
compared with the combs of 
«g. 34. ceratophora stoddartii. upper gallinaceous birds, and appa- 
figure, mule; luwer figure, female 6 fl 
ently serve as ornaments. 
In the genus Chamaeleon we come to the climax of 
difference between the sexes. The upper part of the 
slcull of the male C. Ufurcus (fig. 35), an inhabitant of 
Madagascar, is produced into two great, solid, bony pro- 
jections, covered with scales like the rest of the head ; 
and of this wonderful modification of structure the female 
exhibits only a rudiment. Again, in Cliamieleon OivenU 
(%. 36), from the West Coast of Africa, the male bears 
taken from Dr. Gunther’s magnificent work on the ‘ Eeptiles of British 
India,’ Kay Soc. 18G4, p. 122, 130, 135. 
