DEVELOPMENT OF THE SKULL IN THE LACERTILIA. 
605 
Above these passages the bone is sulcate and lies further outwards, more space being 
wanted for the optic lobes. 
Outside (Plate 43, fig. 8), the prootic forms the front margin of the “fenestra ovalis,” 
whilst a spur of the opistlrotic divides this from the “fenestra rotunda” (fig. 8 
The “foramen ovale” (Y) is perfected in front by the alisphenoid ( cd.s .), which is 
very large as a region, but is only marked out, as it were, in cartilage; for there are 
three large membranous fenestrse enclosed, for the most part, by the alisphenoidal bands 
(Plate 43, figs. 2, 7, 8, cd.s.)* 
The attempt here to form a continuous cranial “ boat/’ like that of a Shark, Skate, or 
Frog, is curiously exhibited in the wicker-work, which is continuous along the top, from 
the front of the orbits to the superoccipital. 
In Birds there is always a large gap in front of the alisphenoid, even in Struthio ; 
but in some Mammals in an early stage the large extended orbito-sphenoid is continuous 
with the nasal roof in front, and touches the ear-sac behind. (See Eschhiciit, ‘ On 
Balcena Japonica, Lac.’; Copenhagen, 1869, plate 2, figs. 1, 2, Jc. ; and my paper on 
the “ Pig’s Skull,” Plate 34, fig. 6, o.s.). 
But in these cases the alisphenoid is small, and does not come near this upper band, 
for the lesser wings, in most Mammals, are much larger than the “ aim majores.” 
In the Bird the fenestra is in the centre of the alisphenoid, but in Lacerta not one 
of the three fenestrse is finished by. the alisphenoid itself. 
The upper band of cartilage runs from the upper lobe of the forked orbito-sphenoid 
(o.s.) to the rounded notch on each side the superoccipital (Plate 43, figs. 7, 8); this 
cartilage overlaps the prootic, and keeps distinct from it. Under this bar there are two 
large squarish fenestrse ; the first is bounded in front by the orbito-sphenoid, and behind 
by the main long ascending bar of the alisphenoid. 
The second is bounded in front by that bar, and behind by the bony prootic. 
The third is under this, and is bounded in front by the bony part of the main ali- 
* I Lave long been familiar with these narrow tapes of cartilage in the smaller Lizards ( 0entropyx 
calcaratus, Anolis sp., Mocoa sp.), but until lately I failed to catch their meaning. I have not yet seen any 
cartilage in the alisphenoidal region of the Chelonia, and in the Chameeleons (old and new-born) there is 
only a narrow stem, ossified in its lower half, close behind the septum orbitarum. 
In the ‘Morphology of the Skull’ (p. 216), Lizards are said to have no alisphenoid; and Professor 
Hdxlet (‘ Elem. Comp. Anat.’, p. 226, fig. 91, 6.) says of the narrow bony alisphenoids of the Iguana, that 
they “appear to represent the orbito-sphenoids.” 
Misled by a fallacious analogy, that of the Mammal’s orbito-sphenoid, where there is a bony bar behind 
the optic nerve, I accepted this suggestion as the truth. Any Bird’s skull might have undeceived me, where 
the skull, so much more specialized and yet truly reptilian, never shows any trace of an “ anterior 
sphenoid ” behind the optic foramen. In Carinate Birds the alisphenoid is largely membranous; it is 
constantly fenestrate (in the young) in the centre, and the foramen ovale is really a large fenestra (“ Fowl’s 
Skull,” Plate 83, fig. 2, as., as.f.), but the orbito-sphenoidal wings are aborted in all but Strutliio camelus, 
even in the “Ratitse;” and the space is filled by one or two membrane-bones on each side. Thus the 
alisphenoid of the Bird is always free in front, although it is continuous with the cranial crest of the 
auditory capsule behind. 
