1864. ] DR. J. £. GRAY ON THE CHAMAELEONID. 465 
6. Revision or THE GENERA AND SPECIES OF CHAMELEONID2, 
WITH THE DESCRIPTION OF soOME New Species. By Dr. 
J. E. Gray, F.R.S., F.L.S., ere. 
(Plates XXXI., XXXII.) 
The Chameleons form one of the most natural family of Lizards, 
as well as one of the most clearly defined. The distinction of the 
species from one another, as is almost always the case in a natural 
group, is difficult, and requires careful study and consideration. 
The species in general are well marked when the characters are elimi- 
nated ; but there are a few species, as Chameleon vulgaris and C. se- 
negalensis, which have a broad geographical distribution, that offer 
several variations such as, if the differences did not appear gradually 
to pass into each other, might induce one to believe that they were 
specific ; but they can hardly be even considered as local varieties, 
for the same variation seems to occur in specimens from different 
localities often situated far apart. 
There is considerable difference in the sexes, especially of the 
horned species which, I believe, was first established in my ‘ Mono- 
graph;’ but this difference does not appear to be common to all the 
species of the Horned Chameleons ; for while the female of C. owenii, 
C. bifidus, and C. parsonii are hornless, the expansions on the sides 
of the nose of C. pardalis, which are analogous to the horn in C. 
bifidus, are as much expanded in the adult female as in the males of 
that species. 
The female specimens are much more common in museums than 
males ; they are perhaps more easily caught when they come to the 
ground to deposit their eggs: and this appears more probable from 
the fact that females containing eggs are often to be found among those 
collected. In some cases, even where there is a series of specimens, 
they are all females; at least I have not, from the external appear- 
ance, been able to discover a male of C. senegalensis or C. dilepis. 
Dr. Hallowell (Journ. Acad. Nat. Se. Philad. vii. 99) thought at 
one time that the occipital lobes were peculiar to the females ; I also 
was once inclined to believe this might be the case, before I had 
seen his remark, from observing that all our specimens of C. dilepis 
appear to be females; but I had the same difficulty in finding any 
males of C. senegalensis or other allied species; and M. A. Du- 
méril specially observes that ‘‘ the cutaneous prolongation is not a 
character only of the female C. di/epis” (Arch. du Mus. x. 174). 
There is considerable variation in the distinction and height of 
the occipital crest in the specimens of C. vulgaris and in some other 
species. This often arises from the animals having been kept in 
confinement without (or with only a very limited supply of) food, until 
the muscles have shrunk. This should make one careful in using 
the height of the crest as a character, more especially as many of 
the specimens in museums have been kept alive in confinement either 
in the country which they naturally inhabit or in some other, as 
collectors like to Wave them alive as pets. 
Proc. Zoou. Soc.—1864, No. XXX. 
