A Contribution to our Knoioledge of the Anatomy of Chamaeleons. 97 
this process to the first four hoops, which are hunched closely together ; 
whereas in the pumilus group, as exemplified in G. ventralis, the corre- 
sponding hoops are not thus bunched together, but occupy positions more 
or less equidistant from one another, just like the hoops more posteriorly 
situated. 
Bibs. — Chamaeleons are remarkable amongst reptiles, excluding snakes 
and serpentiform Hzards, in that most of the post-sternal ribs form com- 
plete hoops. According to Werner there are eight of these hoops in 
Chamaeleon, but only six in Brookesia and BJiavijjJioleon. However, the 
total number of rib-bearing vertebrae is also greater in Chamaeleons, for 
Werner cites fifteen in Chamaeleon, twelve in Bhamjjholeo^i, and nine 
in Brookesia. As a matter of fact, the number of rib-bearing vertebrae 
varies considerably within the genus Chamaeleon. We find that there are 
fourteen in 0. pumikts and C. ventralis, sixteen or seventeen in C. dilepis 
or C. quilensis, whilst the small species, C. gastrotaenia and C. nasuta, 
have only thirteen rib-bearing vertebrae. The smaller numbers most 
probably represent the more primitive conditions. 
Skull 
The various published descriptions and figures of the Chamaeleon skull 
relate mostly to C. vulgaris, which, it may be noted, is one of the most 
specialized members of the family. In an important pioneer paper W. K. 
Parker has dealt at great length with the skulls of C. vulgaris and of 
C. pumilus, but in our judgment his account is in several respects mis- 
leading or inaccurate ; unfortunately his errors have been repeated in the 
text-books. So far as we know a really good account of the Chamaeleon 
skull has not been published : Siebenrock, however, has given a careful 
description of the skull of Brookesia, We have therefore been obliged to 
depart somewhat from our original intention of merely comparing together 
the various types, since in indicating the homologies of particular bones it 
seemed advisable to point out clearly in what respects the views of other 
authors were in conflict with our own . 
Squamosal and prosquainosal.^ — In applying these terms to the inner 
* The following account of Chamaeleon skulls is based on external examination, not on 
sections. 
f Since this account was written, Dr. Broom has kindly sent us a copy of his paper 
" On the Squamosal and Belated Bones in the Mosasaurs and Lizards" (Bull.Amer. Mus. 
Nat. Hist., vol. 32, art, 32, pp. 507-508, publ. Oct., 1913), in which he adduces reasons for 
changing his previously expressed views on the homologies of the bones here considered. 
He is now of opinion that the outer bone in Mosasaurs and Lizards is the squamosal, and 
the inner one the tabulare. He remarks that the inner bone in Mosasaurs is " apparently 
not a bone of the temporal roof at all, except to some slight extent secondarily" : it is 
" more of an occipital element than an element of the temporal roof." 
It appears to us that the identity of the outer bone with the mammalian squamosal is 
still undecided, 
