226 Zoology and Comparative Anatomy 



bottom of the pterygoid [wing-like] processes of the sphenoi- 

 dal [wedge-like] bone. There are the humular or hook-like 

 processes, to which the pharynx [upper part of the gullet] is 

 attached. The great occipital foramen [orifice in the back 

 of the head] for the passage of the spinal marrow from the 

 brain, is situated a little above the preceding. On each side 

 of this foramen [orifice] there are the semilunar condyles 

 [knobs] of the occipital [hind head] bone, which are articu- 

 lated with the atlas [the first bone of the neck] as in the other 

 Mammalia. The remainder of this portion of the skull is 

 occupied by the greater part of the occipital and the mastoid 

 processes. 



The lateral surfaces are formed by the end of the palatine 

 bones anteriorly ; the zygomatic fossa [cavity] and its arch 

 posteriorly. This surface embraces portions of the temporal, 

 occipital, and the sphenoidal bones. 



On viewing the head vertically, we find several interesting 

 peculiarities ; the occipital bone measures more than 3 ft, 

 in thickness, and is very spongy in its texture, whilst the ex- 

 ternal table is at the same time extremely thin ; consequently 

 the specific gravity must be very little, notwithstanding its 

 immense size. The nasal cavities are very largely deve- 

 loped, and in the living animal not only contain the olfactory 

 membrane, but likewise the spiracles, or organs by means of 

 which the whale is enabled to project water to a considerable 

 height above the surface of the ocean. The cerebral cavity, 

 when contrasted with the dimensions of the other portions of 

 the body, is extremely small ; beneath it is the point of union 

 of the vomer with the occipital and part of the ethmoidal 

 bones. "With the exception of the lower jaw-bones, all those 

 composing the head are of a spongy nature, and appear to 

 be formed of a series of laminae. The lower jaw, like the 

 same portions of other animals, and of the human infant at 

 birth, is formed of two distinct pieces of bone, vmited together 

 at the point or chin by symphysis, or a thin layer of inter- 

 vening cartilage ; each one forms a curve terminating in its 

 condyle, and measures 22 ft. in length from the chin to its 

 articulation with the bones of the head. It is extremely hard 

 and compact; the coronoid process which is separated from 

 the condyles by an almost horizontal space, which occupies 

 the place of a semilunar cavity found in the other Mam- 

 malia, affords insertion to the temporal muscle. They arti- 

 culate themselves with the glenoid cavities of the occipital 

 bone, in such a manner as to form a perfect hinge joint. 

 The superior margins of these bones are perfectly smooth, 

 and exhibit not the slightest vestige of any alveolar cavities 



