THE SKULL IN THE CHAMELEONS. 85 
wings (0.8) are seen to be only one third as wide behind as the alisphenoids (a/.s); they 
become only half their hinder width, and then expand again as they pass into the ali- 
ethmoidal lamine (a/.e), where the floor of the skull passes into the roof of the nasal 
pouches. 
Near each other, in the middle of this rewidened tract, the small oblique olfactory 
passages I are seen; and further forwards, under these wings, the orbito-nasal nerves 
(figs. 5 & 4, v’) enter the nasal labyrinth. Where the middle ethmoid passes into the 
septum nasi (Plate XVII. fig. 1, p.e, s.m), there is no “ cranio-facial fenestra,” as in 
Lacerta (op. cit. pl. 43. figs. 1 & 2, c.f. f ) and Trachydosaurus, but, as in the Struthionide 
among Birds, the orbito-nasal partition is continuous, except in the presphenoidal 
region. 
‘The valley over the ethmoidal wings has no ascending ( tegminal) bar of cartilage 
growing oyer it either here or in Lacerta; but all Birds show a spike-shaped remnant 
of the front cranial roof of the ‘ Ichthyopsida” mounting over the channel for the 
olfactory nerves. ‘The endocranial roof, however, is very large behind in the Chameleon, 
as I have just shown. 
The nasal labyrinth, as seen from above (Plate XVII. fig. 4), looks like a quadricellular 
capsule. It has four nearly equalswellings: the hinder pair are circular; and the front pair 
have a helicoid appearance. The postero-lateral edge, in front of the ali-ethmoidal lamin 
(al.e) is sinuously notched; and in the notch are packed, right and left, the nasal 
glands (x. g). This is the position of these glands in certain birds where they are 
moderately developed, as the Rhea and Fowl (Phil. Trans. 1866, pl. 9. fig. 5, n. g, and 
1869, pl. 86. fig. 9, n.g). In Snakes and most Lizards, where the vomers are distinct, 
these glands lie in the vomers as in a dish, and are covered by a lid-like bone—the 
septo-maxillary (Phil. Trans. 1878, pl. 33, and 1879, pl. 42. v, n.g, s.ma). 
Here, in the Chameleon, the high (supero-posterior) position of these glands is the 
correlate (as in the Fowl), of asingle vomer, and of suppression of the septo-maxillaries. 
There is no more than a broad lip-like prenasal cartilage (Plate XVII. figs. 1, 3, & 4, 
p-n), slightly bent downwards in front. Outside, in front, the outer nostrils (e. 2) are 
nearly encircled by a confluent labial (a/.n) or alinasal cartilage, nearly closed above, and 
very similar to the cartilaginous “ annulus tympanicus” of the Frog. In the anteorbital 
region the nasal labyrinth is complicated by an ethmo-palatine cartilage (Plate XVII. 
fig. 3, and Plate XVIII. figs. 6 & 6a, e.pa). 
Endocranium as seen in transverse sections. 
Here the various sections throw a welcome light upon the structure of the nasal 
labyrinth (Plate XVII. fig. 2, and Plate XVIII. figs. 26a). 
In the side view of the septum nasi the cartilage is seen to be thickened at the ends 
and middle of the septum; and the part removed to expose this structure (Plate XVII. 
fig. 2) shows that the pouch on each side is subdivided into two, and that each of these 
VOL. XI1.— Part 11. No. 5.—JJarch, 1881. P 
