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 {oc. c) 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 pitals and basioccipital ; the notochordal " dimple " is obsolete ; its upper edge (Plate 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. m) above it — a small gothic archway. The 

 basioccipital {b.o) 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, l.o) ; its cranial surface is 

 slightly concave. 



Standing on this bone, right and left, we see the exoccipitals [e.o) : but these are not 

 simple now (Plate XVI. fig, 4, e.o, 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 (ix, x, xii), 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.o) is also compound ; for it has gained two additional bones, the 

 epiotics, and therefore encloses the anterior and posterior canals [a. s. c, p. s. c) at their 

 junction. It forms the upper half of the foramen magnum (/. m), rises high up above 

 that passage, and then, suddenly narrowing, forms a crest — that, at its narrow top, on 

 which the interparietal (;i.p) rests. This occipital " tegmen " runs as far forward as to 

 the alisphenoid (Plate XVII. figs. 1, 3, 4, al.s) ; it is wedge-shaped laterally, and 

 emarginate above (Plate XVII. fig. 1 & 4., s.o). In front (Plate XVII. fig. 4, s.o, 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, 3, ei),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 (ej), s.o); 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, pi: o) 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 (o/j). 



In the upper view (Plate XVII. fig. 4) the anterior and posterior canals (a. s. c,p. s. c) 

 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 (b.o), although it mainly lies on the basisphenoid [b.s ; see also the 

 section, Plate XVIII. fig. 12, b.s,pr.o). The meatus intemus (Plate XVII. fig. 1, viii) 



