PHYSETKR MACROCEPHALUS. 35 



The Chacolots or Spermaceti Whales are furnished with teeth 

 only in the lower jaw, and are remarkable for the size of their head, 

 which in some species is equal to the half, and in others to the 

 third, of the whole animal. They belong to the last order of the 

 class Mammalia, in most of the modern systems of Zoology, espe- 

 cially in those of Linneus, Blumenbach, and Cuvier ; while, in the 

 writings of the older naturalists, they have been regarded as an order 

 of fishes. They differ from fishes in the structure of their atlantal 

 extremities, by their mode of breathing, and by their producing 

 young alive and suckling them by means of teats. Eight species 

 of this tribe have been distinguished, all of which afford the fatty 

 substance improperly called spermaceti, which iscontained in cartila- 

 ginous cavities in the bones of the head, where it is held in solution 

 by an oil, which is generally expressed. The Physeter rnacrocephalus 

 is a very large animal, growing to the length of nearly sixty feet, and 

 measuring thirty feet in circumference at the thickest part of the 

 head. The head is of prodigious size, and may be said to exceed 

 the rest of the body in magnitude. It has been compared to an 

 immense box, rounded and obtuse at one end, and rising into a 

 slight convexity at the neck. The back is more or less convex, 

 and near its middle there are the rudiments of a fin, which is 

 short, directed backwards, and truncated at the end. The upper 

 part of the body is of blackish or slate-blue colour, sometimes 

 spotted with white, and the belly is greyish or white. The mouth is 

 wide; the upper jaw much broader than the under, which is long and 

 narrow, fitting as it were into a longitudinal fissure or groove in 

 the upper. The lower jaw is furnished on each side with a row of 

 conical teeth, recurved and pointed at the extremity. On each 

 side of the upper jaw, is a row of holes for receiving the teeth of 

 the lower jaw, and the intervals between these cavities are filled up 

 with the rudiments of teeth, just appearing a little beyond the gum. 

 The eyes are small, furnished with eyelids, and situated at a great 

 distance from the snout. The external orifices of the auditory 

 passages are scarcely perceptible. The tongue is of a square form, 

 and of a livid red colour, and below the snout is the principal 

 cavity that contains the spermaceti. The spiracle, or blow-hole, 

 which appears externally simple, is double within ; it is about six 



