120 MAMMALIA. 



formed in the intestines of the Cachalot, particularly during certsun states 

 of disease. 

 The species of the Cachalots are far from being well ascertained. 



Baljena, Lin. 



The Whales are equal in size to the Cachalots, and in the proportional 

 magn-tude of the head, although the latter is not so much enlai*ged in front; 

 but they have no teeth. The two sides of their upper jaw, which is keel- 

 shaped, or furnished with thin, compact, transverse laminse, called whale- 

 bone, formed of a kind of fibrous horn, fringed at the edges, which serve to 

 retain the little animals on which these enormous Cetacea feed. Their 

 lower jaw, supported by two osseous branches arched externally and to- 

 wards the summit, and completely unarmed, lodges a very thick and fleshy 

 tongue, and when the mouth is closed, envelopes the internal part of the 

 upper jaw, and the whalebone with which it is invested. These organs do 

 not allow whales to feed on such large animals as their size might induce 

 us to imagine. They live on fish, but principally on worms, Mollusca, and 

 Zoophytes, selecting, it is said, the very smallest, which become entangled 

 in the filaments of the whalebone. 



Bal. mysticetus, L. (The Common Whale.) It has long been consid- 

 ered the largest of all animals; but from the late observations of captain 

 Scoresby, it appears that it scarcely ever exceeds seventy feet, a length 

 frequently surpassed by the wrinkle-bellied whales. It has no dorsal fin. 

 To procure its fat or blubber, which is sometimes several feet in thickness, 

 and contains immense quantities of oil, whole fleets are annually equipped. 

 Formerly sufficiently bold to venture into our seas, it has gradually retired 

 to the extreme North, where the number is daily diminishing. Besides oil, 

 it produces black and flexible whalebone, eight or ten feet in length, each 

 individual having from eight to nine hundred strips on each side of the 

 palate. One hundred and twenty tuns of oil are obtained from a single 

 whale. Shell-fish attach themselves to its skin, and multiply there as on a 

 rock, and some of the Balanus family even penetrate into it. 



OF THE OVIPAROUS VERTEBRATA. 



Although the three classes of the Oviparous Vertebrata differ 

 greatly from each other in their quantum of respiration, and in all 

 that relates to it, viz. the power of motion and the energy of the 

 senses, they present several common characters when opposed to 

 the Mammalia, or Viviparous Vertebrata. 



