CHONDROCRANIUM OF EUMECES 181 
(05 b) and for Dermochelys by Nick (12); in Emys, Kunkel 
(12 b) reports a distinct notch for the oculomotor in the margin 
of the fenestra metoptica. Nick holds the division of the 
fenestra metoptica to be the primitive condition—a view which 
gains force from the observations of Schauinsland (’00) and 
Howes and Swinnerton (’01) on Sphenodon in which the origi- 
nally separate foramina later become confluent in a fenestra 
metoptica essentially like that of the lizards. For the crocodiles 
the data are contradictory, but the contradiction is probably due 
in part to differences in the age of the embryos studied. Gaupp 
(05 b) finds separate openings for both nerves, but cites Parker 
(83) as authority for their exit through a common fenestra 
metoptica. Shiino (14) agrees with Parker as regards the 
oculomotorius, but describes the trochlearis as emerging either 
through a separate foramen or through the fenestra optica— 
never through the fenestra metoptica. Shino also emphasizes 
the closure of the fenestra prootica in the crocodiles, and seem- 
ingly holds the union of the taenia marginalis and otic capsule 
unique in this group, in contrast to Sphenodon, lizards, snakes, 
and turtles. The closure of this fenestra by the fusion of the 
taenia marginalis with the otic capsule is clearly described or 
figured in late stages of Sphenodon (Howes and Swinnerton, ’01. 
Schauinsland, ’00, describes an earlier stage in which the fenestra 
is still open), in Dermochelys (Nick, 712), and in Lacerta (Gaupp, 
00). Only in the snakes, where there is practically no lateral 
wall, is the fenestra prootica never closed dorsally. 
6. Lateral wall of orbital subregion 
In striking contrast to the latticework of the temporal sub- 
region, the lateral wall of the orbital subregion consists on each 
side of a single plate of cartilage, sloping downward to the upper 
edge of the septum interorbitale, thus forming a sort of trough, 
the solum supraseptale (fig. 1, sol.s-s.), for the support of the 
olfactory lobes and the anterior part of the cerebral hemi- 
spheres. That the two plates of the solum fuse rather with the 
septum than with one another (as already noted by Gaupp) is 
