in.] THE CRANIAL SKELETON. 129 



Sirenia, and the Cetacea, they look upwards, and open quite 

 on the superior aspect of the skull. The same may be said 

 of those animals with a short proboscis, the Tapirs and the 

 Saiga Antelope. 



The occiput may slope so forward that much more of it 

 may be seen (when the skull is viewed from above) than in 

 man, as is the case, e.g., in the Cape Mole (Chrysochloris\ 

 the Elephant, and the Porpoise. It may, on the contrary, 

 be hidden by the projection of a large lambdoidal crest, as 

 in the Gorilla and Hyaena. 



FIG. 1 1 5. UPPER VIEV/'O? THE SKULL OF A DOLPHIN (Defy/units 

 {After Ciivier ) 



f, occipital condyles ; e, median ethmoid in nasal fossae ',_f, frontal, overlapped by 

 tux, maxilla : n, nasal ; p, parietal, driven down quite to the side of the skull ; 

 /;//, pre-maxilla (here enormous) ; so, supra-occipital. 



It is possible that this region may be in large part mem- 

 branous, as in some Rays. 



On the contrary, great bony productions may exist, as in 

 Ruminants ; either permanent bony cores sheathed with horn 

 as in the Ox, Goat, &c., or else bony developments (antlers) 

 which are annual in their growth and decay. 



There may be four bony cores, as in the existing little four- 

 horned Antelope and in the great extinct Sivatherium. 



The roof of the cranium may falsely appear to be large and 

 smooth, as in the Turtle and in the Rodent Lophiomys. In 

 them the real skull is disguised by the outgrowth of bony 

 lamellae, which, meeting together, arch over the temporal fossae, 

 and make the skull look capacious when it is not really so. 



The inferior region is very rarely divisible into the three 

 K 



