CETACEA. 149 



substance for which they are principally hunted, as the body does not yield a large proportion of 

 blubber : these cavities, however, are very distinct from the true cranium, which is rather small, is 

 placed under their posterior portion, and contains the brain as usual. It appears that cavities filled 

 with this spermaceti, or adipocire as it is called, are distributed to several parts of the body, communi- 

 cating -with those which fill the mass of the head ; they even ramify through the external fat or 

 blubber. The odorous substance known by the appellation ambergris appears to be a concretion 

 formed in the intestines of the Cachalots, particularly during certain states of disease, and, it is said, 

 chiefly in the coecum. 



The species of this genus are by no means well determined. Tliat which appears most common, the P/i. tnticro- 

 cephalus of Shaw and Bonaterre, but not of Linnaeus, has a mere callous prominence instead of a dorsal (in ; there 

 are from twenty to twenty-three teeth on each side of the lower jaw, and small conical ones hidden beneath the 

 gum in the upper : its blow-hole is single, and not double as in the greater number of Cetacea ; neither is it 

 symmetrical, but is directed towards the left, and terminates on that side on the front of the muzzle, which latter 

 is truncate.* In addition to this, it is stated that the left eye is often smaller than the other, for which reason the 

 whalers endeavour to attack it on that side. This species nuist be very extensively distributed, if, as is asserted, 

 it alone furnishes the whole of the spermaceti and ambergris of commerce, for these substances are brought from 

 both the north and south. Cachalots without a dorsal tin have even been taken in the Adriatic. 



The Physeters, Lacepede, — 

 Are Cachalots with a dorsal fin. 



Two species only have been distinguished (jnicrops, and tursio or mu!ar), and those merely by the equivocal 

 character of having the teeth curved or straight, blunt or pointed. These animals are found both in the Mediter- 

 ranean and glacial seas, in the latter of which they are reputed to be cruel enemies to the Seals. 



The Whales (Bahena, Lin.) — 

 Equal the Cachalots in size, and in the proportional dimensions of the head, altliough the latter is not 

 so much enlarged in front ; but they have no teeth whatever [beyond the rudiments of them in the 

 fffital state]. Tlie two sides of their upper jaw, which is keel-shaped, are furnished with thin, trans- 

 verse, serrated lamina?, termed baleen or whalebone, composed of a sort of fibrous horn fringed at the 

 edges, which serve to retain [and strain from the water] the minute animals on which these enormous 

 cetaceans feed. Their inferior jaw, supported by two osseous branches arched outwardly and upward, 

 without any armature, affords lodgment to a very thick and fleshy tongue, and, when the mouth is 

 closed, envelopes all the internal part of the upper jaw and the baleen with which it is invested. These 

 organs do not allow Whales to feed on such large animals as their vast size would lead to imagine. 

 They subsist on fish, but principally on worms, mollusks, and zoophytes, and it is said that they 

 chiefly take the very smallest, which become entangled in the filaments of the baleen. Their nostrils, 

 better organized for smell than tho.-e of the Dolphins, have some ethmoidal laminae, and appear to 

 receive some small olfactory nervous filaments. They have a short coecum. 



The Great Northern Whale (B. mysticetus, Lin.) was long considered to be the largest of known animals, but it 

 appears from the recent observations of Capt. Scoresby, that it scarcely ever exceeds seventy feet in length, which 

 the Rorquals or Whales with wrinkled bellies frequently surpass. It has no dorsal fin. To procure its blubber, 

 often several feet in thickness, and yielding an immense quantity of oil, whole fleets are annually equipped in 

 pursuit of it. Formerly bold enough to venture into our seas, it has gradually retired to the far north, where the 

 number is daily dimiuishing. Besides its oil, it furnishes the black and flexible whalebone of commerce, the pieces 

 of which are eight or ten feet long, and to the number of eight or nine hundred on each side of the palate. A 

 hundred and twenty tons of oil are obtained from a single individual. Shelled Mollusks attach themselves to its 

 skin, and multiply there as upon a rock ; the Dalaniis family even penetrate into it. The excrement is of a fine 

 red colour, and atfords a tolerable dye. There is a very similar species in the Antaictic seas. 



Other species. 



The RoaauALs {Balcenoptera, Lacepede), — 



Have a dorsal fin, and are subdivided according as the belly is smooth or wrinkled. [As the former 

 section is unquestionaijly fouiuled in error, as suspected by Cuvicrf, we pass to those] which have the 

 throat and under-parts wrinkled with deep longitudinal folds, and consequently susceptible of great 

 (lilatatiou, the intent of which, in their economy, is yet unknown. 



• We have verified on two crania tiiis want of symmetry in the i iniluces us tu credit the inequality of the eye^ mentintied i)y K^t^'Ie. 

 spiri.cie, announced hy Dudley, Anderson, aiui Sweciiiiutr, which 1 t The wrlnliied belly being simply filled out with water. 



