MORPHOLOGY OF THE VERTEBRATE SKULL 7 
Bezeichnung Alisphenoid dirfte kiinftig bei keinem Sauropsiden 
mehr beniitzt werden. Der bisher so bezeichnete Knochen ist 
ident mit den Orbitosphenoid.”’ 
Last year the present writer had the privilege of studying the 
skulls of Tyrannosaurus and other Dinosaurs in the American 
Museum of Natural History in collaboration with Professor 
Osborn (712) and Doctor von Huene, and was inclined to accept 
the view of the latter that the principal elements in the walls 
of the reptilian skulls are not alisphenoids but orbitosphenoids. 
Further study, however, has led to the following considerations: 
In mammals? the alisphenoids are lateral to the basisphenoid and 
pituitary fossa, they connect posteriorly with the prodétics and 
superiorly with the parietals, they are pierced posteriorly by 
nerve V3, and they lie outside of the Gasserian ganglia and behind 
the sphenorbital fissure (for nerves III, IV, VI); on the lower 
surface of the skull they are postero-external to the pterygoids 
and laterally embrace the basisphenoid; they are also chiefly 
external to the foramina for the internal carotids. 
In Cynodonts (fig. 6) there are a pair of elements showing 
strong resemblances with the mammalian alisphenoids and so 
named by Broom. In the internal view of the Cynodont skull 
as figured by Broom (’11), it is seen that these alisphenoids are 
anterior to the prodtics, lateral to the basisphenoid and pituitary 
fossa, inferior to the parietals. They also lie in front of the fora- 
men prooticum (for nerves V2, V3); to judge from the relations of 
the small process running from the proétic upward, inward and 
forward, it seems probable that the supposed alisphenoids also 
lay outside the Gasserian ganglia; their anterior border looks 
much like the posterior boundary of the sphenoidal fissure (fora- 
men lacerum anterius), hence they were probably posterior to 
the exit of nerves II, III, V1, VI, like the alisphenoids of mam- 
mals. On the lower surface of the skull the bones called ali- 
sphenoid were postero-external to the pterygoids and embraced 
the basisphenoids laterally just in front of two openings which 
Broom identifies as ‘‘probably for the carotids.’”’ Thus the evi- 
3 See the figures of the skull in embryo marsupials, edentates, insectivores, 
etc., as figured by Broom, Parker and others (especially Parker, 1885). 
