100 PROF. W. K. PARKER ON THE STRUCTURE OF 
Hatteria; yet that of the latter (see Giinther, Phil. Trans. 1867, pl. 1) is less aberrant 
in many things than that of the Chameleon. The continuity of the stapes with the 
hyoid arch is not a unique character ; that which is unique is the binding of the cheek 
to the quadrate by a quadrato-jugal, a character which Hatteria has in common with 
Chelonians, Crocodilians, and Birds. That type, however, has the vomers large and 
distinct, and an epipterygoid the largest seen in any Reptile. 
The most instructive skull for comparison with that of the Common Chameleon 
belongs to a Mexican Iguanian Lizard, viz. Lamanctus longipes. Its size is about the 
same ; and it is exquisitely ornate, aud possesses a very large interparietal crest. Yet in 
nearly every thing this remarkable skull is normal, except in the development of the 
crest. As in the Chameleon, the frontals are ankylosed together; but the fontanelle, 
although bounded by the frontal, lies on the edge of the parietal. That bone sends 
outwards and backwards the normal “horns,” that are articulated to the parotics, 
supratemporals, and squamosals in the normal manner; but it has also a large, flat, 
vertical crest, formed by the gradual narrowing of the parietal bone from before back- 
wards; and this crest, keeping very nearly the line of the general gentle rise of the top 
of the head, extends far backwards beyond the endocranium. But the supraoccipital 
does not rise to meet it; sothat the height of the head behind is much less than in the 
Chameleon. 
In the young of the Common Chameleon and in the adult Dwarf kind, we saw the 
parietals as one bone: in the former a median forward outgrowth, belonging to the pair 
of primary parietals, had yoked them together ; in the latter the three elements were 
seen to be all lost in one large, crested, arched, tuberculate slab of bone. 
In Lemanctus, undoubtedly, the primary bands that formed the beginning of the 
parietal bones rapidly developed a common median outgrowth, that shot up into the 
large lateral crest ; but I question if, at any time, there were three distinct bones. 
In comparing the skull of the Chameleon with that of Lacerta (see Phil. Trans. 1879, 
plate 42), I shall leave out of account the supernumerary bones that are seen over 
the eyes and temples in that typical form, as well as in some others, such as Mocoa 
(a “*Scincoid ”). 
The Common Chameleon differs from the typical Lizards— 
a. In the investing bones: 
1. Their highly ornate character. 
2. The fronta/s are fused together * and contain the fontanelle. 
3. The parietals are broken up into three bones, two parietals and an interparietal ; 
but the former are abortively developed, articulate with the end of the interparietal 
crest, and are ankylosed with the squamosals. 
4. The prefrontals and postorbitals are articulated with each other over the orbit, thus 
excluding the frontal from the outer ring. 
* Lizards are very variable as to this character. 
