THE SKULL IN THE CHAMELEONS. 83 
nerves (I) pierce the narrow floor of this shallow part of the skull, where it is closing in 
above the fore end of the orbital septum. 
The rest is a broad, subquadrate, inflated, double pouch, forming the paired nasal 
capsules (Plate XVII. figs. 3 & 4). 
The occipital condyle (0c. ¢) is semicircular, and receives into its substance the exocci- 
pitals and basioccipital ; the notochordal “dimple ” is obsolete ; its upper edge (Plate 
XVI. fig. 4) is straight, and its lower more than half a circle. This condyle is nearly 
twice as large as the foramen magnum (f. 7) above it—a small gothic archway. ‘The 
basioccipital (4.0) is a large bony wedge, convex behind, at its narrow part, but hollowed 
in front, where it joins the basisphenoid (Plate XVI. figs. 2—4, b.0) ; its cranial surface is 
slightly concave. 
Standing on this bone, right and left, we see the exoccipitals (¢.0): but these are not 
simple now (Plate XVI. fig, 4, ¢.0, op, & Plate XVII. fig. 4); they have coalesced 
with the extended opisthotics. Hence they seem not only to give exit to the 9th, 
10th, and 12th nerves (1x, x, x11), but also to contain the lower and hinder part 
of the posterior and horizontal canals, and to form the large solid parotic wings (op). 
The supraoccipital (s.0) is also compound; for it has gained two additional bones, the 
epiotics, and therefore encloses the anterior and posterior canals (a. s. ¢, p. 8. ¢) at their 
junction. It forms the upper half of the foramen magnum (ff: m), rises high up above 
that passage, and then, suddenly narrowing, forms a crest—that, at its narrow top, on 
which the interparietal (7.p) rests. This occipital “tegmen” runs as far forward as to 
the alisphenoid (Plate XVII. figs. 1, 3, 4, a/.s); it is wedge-shaped laterally, and 
emarginate above (Plate XVII. fig. 1 & 4.,s.0). In front (Plate XVII. fig. 4, s.0, ep) 
this epiotico-supraoccipital ends in five tooth-like projections, the middle of which 
is the crest, whilst the outer two are part of the original epiotic. On account of the 
curious manner in which the hind roof is, so to speak, tilted forwards, the epiotic rides 
obliquely over the top of the prootic (Plate XVII. figs. 1, 5, ep, pro). 
The prootics (Plate XVI. fig. 1, and Plate XVII. figs. 1, 3-6, pro) contain most of 
the anterior and horizontal canals (a. s. c, h. s. c) ; they lie below the epiotic region of the 
compound roof-bone (ep, s.0); and the two eminences caused by the ampulla of those 
canals are close behind the foramen ovale (Plate XVII. figs. 3, 4, v). On the inside 
of the skull (Plate XVII. fig. 1, pr. 0) the prootic is seen in front of the triradiate syn- 
chondrosis, in the fork of which we see the epiotic (ep), and behind the stem the 
opisthotic (op). 
In the upper view (Plate XVII. fig. 4) the anterior and posterior canals (a. s. ¢, p. s. ¢) 
are seen projecting from the prootics and opisthotics, and meeting in the epiotic to unite 
into one tube; the horizontal canal is beneath the anterior, and is therefore out of sight 
in this aspect (see fig. 6, h.s.c) In the inner view the prootic is seen to rest, behind, on 
the basioccipital (0.0), although it mainly lies on the basisphenoid (4.8; see also the 
section, Plate XVIII. fig. 12, .s, pr.o). The meatus internus (Plate XVII. fig. 1, vim) 
