636 
MR. W. K. PARKER OK THE STRUCTURE AND 
The comparison of the Lizard’s skull with that of the Snake, given in my last paper 
(Phil. Trans., 1878, Part II.), is of great interest. 
In some respects they are much alike, and the development is the same, essentially, 
in both; but there are many delicate specializations in the Lizard’s skull that are not 
to be found in that of the Serpent. Thus the nasal capsule is more labyrinthic; the 
auditory apparatus more developed, having a tympanic cavity, and a separate sta¬ 
pedial muscle; for the senses of this creature are more refined, and it belongs to a 
higher type. 
The cranial walls have a remarkable, and yet very delicate, development; the 
“ cliondrocranium ” is much more developed than that of a Snake, but it is for the 
most part a mere piece of basket-work. 
The “ exoskeletal ” bones, outside this basket-work, and outside the labyrinths of 
the ears and nose, are very numerous ; and their interpretation can only be made by one 
who is familiar with the outworks of the skull in Amphibia and Fishes. 
As this is but my second paper on the Reptilian skull, and as others are in hand, I 
shall defer further comparisons until more work is wrought, and brought out. 
List of Abbreviations. 
The Roman figures indicate the nerves or the nerve foramina. 
o 
ag. ' Angular. 
CO. 
Columella. 
all. Allantois. 
c.op. 
Opisthotic cartilage. 
cd.s. Alisphenoid. 
cr. 
Coronoid. 
cir. Articular. 
c.tr. 
Cornua trabeculae. 
ar.c. Articular cavity. 
c.ty. 
Tympanic cavity. 
a.s.c. Anterior semicircular canal. 
d. 
Dentary. 
au. Auditory organ. 
e. 
Eye. 
b.hy. Basihyal. 
e.n. 
External nostril. 
b.o. Basioccipital. 
e.o. 
Ex-occipital. 
b.pg. Basipterygoid. 
ep. 
Epiotic. 
hr. Branchial arch. 
e.pa. 
Ethmo-palatine. 
b.s. Basisplienoid. - 
epg. 
Epipterygoid. 
C 1 . Fore brain. 
e.st. 
Extra-stapedial. 
CK Cerebral hemispheres. 
eu. 
Eustachian canal. 
C 2 . Mid brain. 
f 
Frontal. 
C 3 . Hind brain. 
f.b.pg. Facet for basi-pterygou 
C 3 ". Cerebellum. 
fm. 
Foramen magnum. 
c. hr. Cerato-branchial. 
f°- 
Fontanelle. 
c.f.f. Cranio-facial fenestra. 
fo. 
Fenestra ovalis. 
chi. Cochlea. 
f-P9- 
Facet for pterygoid. 
c.hy. Cerato-hyal. 
fi'- 
Fenestra rotunda. 
cl, Visceral cleft. 
li. 
Heart. 
