216 B. NATURAL HISTORY. 
If we now turn to the Rhynchocephalia, as represented by Sphe- 
nodon,* we find the exoccipital greatly prolonged laterally, and 
carrying with it the opisthotic. It is carried apparently beyond 
any connection with the prootic (alisphenoid of Giinther), but is 
less distant from the supraoccipital, or rather the epiotic (parocci- 
pital, Giinther), which is here, according to Giinther, not entirely 
separated from the supraoccipital, as in the Testudinata, though 
more so than in the latter. Its superior and anterior extent is 
remarkable in this genus, forming a connection with the postorbi- 
tal above and the malar below, peculiarities not noticed in any 
other reptile. Superiorly it rises into the parieto-quadrate arch, 
which it forms with the squamosal, the parietal not entering it; 
another peculiarity, the only parallel to which is to be found in the 
Anomodontia, where this arch is however depressed into close con- 
tact with the occipital segment of the skull. 
The type exhibited by the Lacertilia is intermediate between 
that of the last and that of the Tortoises, and serves to reconcile 
them. Here, also, the opisthotic 
is carried beyond connection with 
the other otic elements. In Igu- 
ana it contributes largely to the 
formation of the parieto-quadrate 
arch, but with the parietal instead 
of the squamosal, and on the under 
instead of the upper side, as in the 
Fig. 12.—Iguana tuberculata; pos- genus Sphenodon. (See figs. 13, 
terior arches removed. 14, OpO.) In Chameleo it is a 
mere wedge articulating with the proximal end of the quadra- 
tum, and not entering into the parieto-quadrate arch. 
Fig. 18. —Iguana tuberculata; lateral view, with arches. 
* I rely on the figures and descriptions of Giinther, in his paper on the Anat- 
omy of Hatteria (Philos. Trans., London, 1867). 
