286 EDWARD PHELPS ALLIS, JR. 
palatinus lying directly beneath the floor of the cavum cere- 
brale cranii. Thus this canal is, as Fuchs says, not the homo- 
logue of the canalis parabasalis of reptiles, and also not the 
homologue of that same canal in fishes. 
The fenestra hypophyseos of the Amphibia is then the homo- 
logue of the pituitary opening of the brain case of fishes, and 
not of either the fenestra hypophyseos or the fenestra ventralis 
myodomus. 
The antrum petrosum laterale of Driiner’s (’01) descriptions 
of the Urodela represents some part of a trigemino-facialis cham- 
ber, and quite certainly its pars jugularis only (Allis, ’14 d), the 
pars ganglionaris of the chamber then being enclosed within 
the cranial wall. The lateral wall of the pars jugularis of the 
chamber is formed by that part of the palatoquadrate terminat- 
ing in the processus oticus, the processus ascendens quadrati, 
which is the homologue of the pedicel of the alisphenoid of fishes, 
forming the lateral wall of a space which corresponds to the 
orbital opening of the myodome of Amia. There, however, 
apparently is, in these vertebrates, no cartilage corresponding 
to the floor of that opening of Amia. 
In the Anura the conditions are apparently similar to those 
in the Urodela, for, in embryos of Rana, Gaupp (’93 b) shows 
the trigemino-facialis ganglion lying within the chondrocranium. 
REPTILIA 
In my work on the mail-cheeked fishes, I came to the conclu- 
sion that there was, in the pituitary region of the chondrocranium 
of Lacerta, a ‘space of uncertain dimensions’ which corresponded 
to a part, if not the whole, of the myodome of fishes. This 
space was between the cartilaginous floor of the cranial cavity 
and a membrane which was assumed to overlie it and to form the 
actual floor of the cavum cerebrale cranii, but I could not then 
find this membrane described. It is, however, shown by Gaupp 
(02, fig. 6, p. 172), well developed, in a figure of a cross- 
section through the prootic region of a 32-mm. embryo of 
Lacerta, and in the space between it and the cartilaginous 
basis cranii the hypophysis and the nervi abducentes are shown. 
