VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. 313 



and in birds, this cavity constitutes the principal bulk of the head. This is per- 

 haps most remarkable in the spermaceti whale ; for on a general view of the bones 

 of the head, it is impossible to determine where the cavity of the skull lies, till 

 led to it by the foramen magnum occipitale. The same remark is applicable to 

 the large whalebone and bottle-nose whale ; but in the porpoise, where the brain 

 is larger in proportion to the size of the animal, the skull makes the principal 

 part of the head. 



Some of the bones in one genus differ from those of another. The lower jaw 

 is an instance of this. In the spermaceti and bottle-nose whales, the grampus, 

 and the porpoise, the lower jaws, especially at the posterior ends, resemble each 

 other ; but in both the large and small whalebone whales, the shape differs con-' 

 siderably. The number of some particular bones varies also very much. The 

 pike whale has 7 vertebrae in the neck, 12 which may be reckoned to the back, 

 and 27 to the tail, making 46 in the whole. In the porpoise there are 5 cervical 

 vertebrae, and 1 common to the neck and back, 1 4 proper to the back, and 30 

 to the tail, making in the whole 5 1 . The small bottle-nose whale, caught near 

 Berkeley, in the number of cervical vertebrae resembled the porpoise '; it had 1 7 

 in the back, and 37 in the tail, in all 60. In the porpoise, 4 of the vertebrae of 

 the neck are anchylosed ; and in every animal of this order, which I have exa- 

 mined, the atlas is by much the thickest, and seems to be made up of 2 joined 

 together, for the 2d cervical nerve passes through a foramen in this vertebra. 

 There is no articulation for rotatory motion between the 1 st and 2d vertebrae of 

 the neck. 



The small bottle-nose whale had 18 ribs on each side, the porpoise 16. The 

 ends of the ribs that have 2 articulations, in the whole of this tribe, I believe are 

 articulated with the body of the vertebrae above, and with the transverse pro- 

 cesses below, by the angles ; so that there is one vertebra common to the neck 

 and back. In the large whalebone whale the first rib is bifurcated, and con- 

 sequently articulated to 2 vertebrae. The sternum is very flat in the piked whale; 

 it is only one very short bone ; and in. the porpoise it is a good deal longer. In 

 the small bottle-nose it is composed of 3 bones, and is of some length. In the 

 piked whale the first rib, and in the porpoise the first 3, are articulated with the 

 sternum. As a contraction, corresponding to the neck in quadrupeds, would 

 have been improper in this order of animals, the vertebrae of the neck are thin 

 to make the distance between the head and shoulders as short as possible, and in 

 the small bottle-nose whale are only 6 in number. 



The structure of the bones is similar to that of the bones of quadrupeds ; they 

 are composed of an animal substance, and an earth that is not animal : these 

 seem only to be mechanically mixed, or rather the earth thrown into the inter- 



VOL. XVI. S s 



