78 PROF. W. K. PARKER ON THE STRUCTURE OF 
shoulder-girdle and sternum (‘Shoulder-girdle and Sternum,” plate xi. figs. 4-6, 
p. 122); and I have no doubt that every part of its organization, if well worked out, 
would show some very important modifications. 
But in the culminating types of any group whatever, some archaic characters are sure 
to crop up. I find this “ survival” in the Frog among the Anura, and in the Nimble and 
Green Lizards among the Lacertilia : in the former, which is the best pattern-form for the 
group, there are two or three characters that are exceptional; and in the latter, the 
most refined and delicate forms in the Lizard group, the whole cranial roof, from snout 
to occiput, might have been directly, and not remotely, derived from some most ancient 
Ganoid fish (see “On the Skull of the Lacertilia,” Phil. Trans. 1879, part ii. plate 42, 
p- 597). 
SKULL OF THE ADULT CHAMELEON (Chameleo vulgaris). 
Seen from above, or below, the outline of this skull is a long oval; from the side it is 
seen to have a short, steep face, almost as steep and short as that of a Tortoise, and to 
be surmounted behind by an exorbitant three-limbed crest; it has huge eye-sockets, and 
a steep hinder region. 
In this species, and still more in other larger and more bizarre kinds, the marginal 
bones of the skull-roof are very large, crested, and adorned with knobs and prickles, 
as though it were showing a Selachian atavism, and had compounded its investing 
bones out of the shagreen prickles and the ossified skin of some such Placoid forefather. 
The roof dips ; and the frontal is not seen from the side; and the whole upper outline, 
looked at from above (Plate XVI. fig. 3), is like the plan of a double arch, with the coronal 
suture as a common basal line. But the keystone in front, the single premaxillary (pz), 
is wedged in between the fore face below and the fore skull above. The hinder key- 
stone, the interparietal (7.p), binds and finishes the arch that springs from the great 
auditory wings (Plate XVI. fig. 4). The lower edge of the fore part of the skull 
spreads out into a much broader structure than the upper; its margins are the maxil- 
laries (ma) ; the upper outline of the fore part is formed by the pretrontals (p.f) (super- 
ficial or dermal ethmoids). ‘The middle of the upper margin is formed by the post- 
orbitals (pt.o); and the form is finished behind by a pair of compound bones, the 
squamoso-parietals (sg. p.). Thus the single adult frontal (f) is completely enclosed, 
and forms the centre of the somewhat sunken roof, which is finished behind by the base 
of the huge crested interparietal (7.p). 
The lower surface shows a broad latticework, very complex, and very compound ; it 
is composed of subcutaneous plates and of submucous bones (that are ectostoses in lower 
types), of cartilage, and of cartilage-bones; for in this view we see the basis cranii, 
the complex palate, and the marginal bones of the face. ‘The side view (fig. 1) shows 
the steepness of the face, the height of the crest behind, the strength of the flat jaws, 
