688 



MANUAL OF ZOOLOGY. 



North Pacific we meet with the B. Japonica along with the B. mysticetus 

 or Right Whale of the North Atlantic (Van Beneden). 



The only remaining members of the Balcenidce which require notice are 

 the Rorquals and Hump-backed Whales, constituting the group of the 

 ' ' Furrowed " Whales. These are collectively distinguished by having the 

 skin furrowed or plaited to a greater or less extent, whilst the baleen-plates 

 are short, and there is a dorsal fin. The specific determination of these 

 animals is a matter of great difficulty, but there would appear to be prob- 

 ably three well-marked genera : I. The genus Megaptera, including the 

 so-called Hump-backed Whales, in which the flippers are of great length, 

 from one-third to one-fifth of the entire length of the body. 2. The genus 

 Balcenoptera, comprising the so-called Rorquals or Piked Whales, in which 

 the flippers are of moderate size. 3. The Finner Whales proper (Physalus). 



In all these genera there is a dorsal adipose fin, so that they are all 

 "Finner Whales." The Balanopterce reach a gigantic size, being some- 

 times as much as eighty or one hundred feet in length. They are very 

 active animals, however, and their whalebone is comparatively valueless, 

 so that the whalers rarely meddle with them, though they are not uncom- 

 mon, and are often driven ashore on our own coasts. 



Fam. 2. CatodontidcB. The family of the Catodontida or 

 Physeteridcz comprises the Sperm Whales or Cachalots, with 

 which we commence the series of the toothed Whales (Odon- 

 toceti). They are characterised by the fact that the palate is 

 destitute of baleen- plates, and the lower jaw possesses a series 

 (about fifty-four) of pointed conical teeth, separated by inter- 

 vals, and sunk in a common alveolar groove, which is only 

 imperfectly divided by septa. The upper jaw is also in reality 

 furnished with teeth, but these do not cut the gum. 



The best-known species of this family is the great Cachalot or Sper- 



Fig. 384. Spermaceti Whale (Physeter macrocephalus}. 



maceti Whale {Physeter macrocephalus, fig. 384). This animal is of enor- 

 mous size, averaging from fifty to seventy feet in length, but the females 



