GENERAL REVIEW OF THE SKULL. 63 
coalesce with, the foramen lacerum posterius. 
7. The glenoid foramen is always very small, and 
is sometimes not to be detected. | 
8. The alisphenoid canal may be present or 
absent. 
9g. The suborbital foramen is always rather large ; 
but never as large relatively as in Lutra and Exhydra. 
It is largest in 7rechechus. 
10. The frontal postorbital process, present in 
Otarza and Trichechus, is never more than a rudiment 
in the Phoczde. 
11. [The zygomatic postorbital process is formed 
both by the malar and squamosal in the Phoczde, 
mainly by, the malar in the O/aria, and entirely by 
it in Zvechechus. 
12. The ali-sphenoid and parietal always join by 
a narrow process of the latter bone. 
13. The premaxilla never ascend to join the 
frontals. 
14. There is never a lachrymal foramen. 
15. The basis cranii is nearly always bent, so as 
to be convex downwards. 
16. The anterior nares are quite terminal in 7yz- 
chechus; rather more distant from the end of the 
muzzle in Ofarza, and not at all terminal, but looking 
more or less exteriorly, upwards as well as forwards, 
in the Phoczde. 
17. The opening represents both the foramen 
rotundum, and the spheno-orbital fissure. 
