PART L-CETACEA. 



INTRODUCTION. 



The order of Cetacea, as established by naturalists, includes all species of 

 mammalia which have been created for inhabiting the water only ; and although 

 their forms bear a strong resemblance to those of the ordinary piscatory tribe, still 

 they are animals having warm blood, breathing by means of lungs, and frequently 

 coming to the surface of the water to respire. In nearly all Cetaceans, the nostrils 

 — termed spiracles or spout- holes — are situated on the top of the head. Through 

 these the thick vaporous breath is ejected into the atmosphere to various altitudes, 

 according to the nature of the animal in this particular respect ; and through the 

 same orifices a fresh supply of air is received into its breathing system. Although 

 the Cetaceans are strictly regarded as mammals, they have no true feet ; their pec- 

 torals being in the form of heavy, bony, and sinewy fins, while the posterior 

 extremity of the body terminates in a broad cartilaginous limb of semi -lunar shape, 

 frequently termed the caudal fin or tail, but known among whalemen as the 

 "flukes," the lobes of which extend horizontally. 



The dififerent species of Cetaceans are numerous ; hence they have been divided 

 into groups, the most prominent of which are the Whalebone Whales, the Cachalots 

 or Sperm Whales, and the Dolphins. The group of BalcenidcB, or Whalebone Whales, 

 embraces all those which are destitute of teeth when adult, and whose palate is 

 lined on each side with rows of horny plates, called whalebone or baleen, which 

 are fringed on their inner edges. This part of the animal's organization is pecul- 

 iarly adapted to the nature of its food, which consists of zoophytes, mollusks, crus- 

 taceans, and small fish. The group of Sperm Whales comprises those with inordi- 

 nately massive heads, whose upper jaw has only rudimentary teeth, or none at 

 all ; whose lower jaw is narrow, rounded toward its anterior extremity, elongated 

 and filling the furrow in the upper one, and furnished on each side with a row 

 of heavy conical teeth, with which to procure and devour the enormous cuttle-fish 



MaBINE M.iMMALS. — 3. 



