98 
Transactions of the Boyal Society of South Africa. 
and outer elements respectively of the supratemporal " arch of a lizard's 
skull we do so on the recommendation of Drs. Broom and Gadow, to each 
of whom we are greatly indebted for information regarding the probable 
homologies of these elements in general. However, we are limiting the 
present question to a brief comparison between the various forms of 
Chamaeleons and some other lizards in respect to these bones. In the 
posterior part of the supratemporal arch of the common Chamaeleons 
(C vulgaris or C. quilensis) two bones are found, a larger one extending 
the whole distance from the tip of the parietal to the postfrontal and 
jugal, and a small inconspicuous sheathing bone only seen in hind view 
and stretching but a short distance above the quadrate. Comparing 
these with the bones of a typical lacertilian, such as Varanus, we believe 
that the larger one is homologous with the bar (the ]jrosqua?nosal) which 
in Varanus connects the quadrate with the postfrontal ; whilst the very 
small bone is the homologue of the inner element (the squamosal) which 
passes from the quadrate to the lateral part of the parietal. This view of 
their homology does not appear to have been held by some other writers 
on Chamaeleons. Owen spoke of the large bone as the mastoid, implying 
its homology with the inner bone of Varanus. Boulenger, in the British 
Museum Catalogue of Lizards, calls this same bone the " supratemporal," 
a term which he uses in the same work for the inner bone in other lizards. 
Huxley seems to have held the same view of its homology. On the other 
hand, in W. K. Parker's account of the structure of the skull in 
Chamaeleons (Trans. Zool. Soc, xi., p. 77 ct seq.), in C. K. Hoffmann's 
work (Bronn's, Tierreich), and in Werner's monographs (Das Tierreich, 
1911, and Zool. Jahrbuch, Sept., 1902, vol. xv.) the large bone is 
styled the squamosal, all these authors using that term in other lizards 
for the bone which we are now calling the prosquamosal. Dr. Gadow > 
in a short account of the Chamaeleon skull (Oamb. Nat. Hist., p. 568), 
describes the two bones as partially fused, and is not clear regarding their 
homologies, for he says, " the parietal bones united into one, extends 
backwards far beyond the occiput, and the tip of this projection is met 
by a much-elongated supratemporal bone which, partly fused with the 
squamosal, helps to enclose a huge supratemporal fossa"; but in his 
accompanying figure the much elongated bone is simply labelled the 
squamosal. 
The prosquamosal and the much reduced squamosal show various 
degrees of development in different members of the family of Chamaeleons. 
The prosquamosal is largest in the dilepis group : in these species it 
stretches from the tip of the parietal to the orbital region, where it forms 
sutures both with the postfrontal and the jugal. A similar arrangement 
is found in the Malagasy species, G. lateralis, G. nasuta, and G. brevicornis. 
In a single specimen of G. gastrotaenia examined, the prosquamosal does 
