564 



CETACEA. 



B. With the head of immoderate size, 

 equalling one-third the length of the 

 body. 



Family I. CATODONTIDjE. Teeth nu- 

 merous, conical, but developed only in 

 the lower jaw. External nostrils or 

 blow-holes confluent ; no ccecum. 

 Genus CATODON. No dorsal fin. 

 Ex. Catodon macrocephaius ; Physeter 

 macrocephalus, Shaw. The great Sper- 

 maceti Whale. 



Genus PHYSETER. A dorsal fin. 

 Ex. Physeter Tursio, Linn. The High- 



finned Cachalot, Shaw. 

 Family BAL^NID^. No teeth; their 

 place supplied by the plates of baleen 

 or whalebone attached to the upper jaw. 

 Blow-holes distinct; a cuecum. 

 Genus BAUENOPTERA. A dorsal fin ; 

 pectoral integument plicated ; baleen- 

 plates short. (See Jig. 259.) 

 Species. Bal&noptera Boops, Cuv. ; the 



Jubarte or great Rorqual. 

 Balanoptera rostrata, Lacep. ; the Piked 

 Whale of Sibbald and Hunter, sus- 

 pected by Cuvier to be the young state 

 of the Baltfiwptera Boops. 

 Bal&noptera Musculus, Cuv.; the Me- 

 diterranean Rorqual. 



Baltenoptera Antarctica, Cuv.; the South- 

 ern or Cape Rorqual. 

 Genus BALDEN A. No dorsal fin; pectoral 

 integument smooth ; baleen-plates long. 

 Species. Baltena mysticetus, Linn. The 

 great Whalebone Whale of Hunter; 

 great Mysticete. 



Bul&na Australis,Cuv. The Cape Whale.] 

 ORGANS OF MOTION. Swimming is the 

 principal mode of progression of the Cetaceans, 

 but the Phytophagous species appear to have 

 the power, in order to feed upon marine plants, 

 of crawling and walking at the bottom of the 

 sea by means of their anterior members, which 

 in other Cetaceans are exclusively natatory 

 organs. 



The head, in all, has so little mobility, that 

 its axis can be but slightly altered, without 

 that of the body altering also. 



In the form and composition of the skull 

 the Cetaceans of both tribes present many im- 

 portant differences, as compared wtth other 

 mammiferous animals. In the Herbivorous 

 genera the bones are dense and massive, and 

 where they are not anchylosed their connection 

 is of a loose kind. In the Dugong the skull is 

 more especially remarkable for the large size of 

 the intermaxillary bones (a, a, Jigs. 246, 247), 

 which extend backwards as far as the middle 

 of the temporal fossae, and are bent down ante- 

 riorly over the symphysis of the lower jaw, so 

 as to terminate nearly on a level with its infe- 

 rior margin. This extent and shape is required 

 in the Dugong for the lodgement of the perma- 

 nent incisors (b, b), which are developed to a 

 large size, one in each intermaxillary bone, 

 and consequently the nostrils are placed much 

 higher and further from the mouth than in the 

 Manatee, in which, in consequence of the small 

 deciduous incisors having no successors, the 



Fig. 246. 



Skeleton of the Dugong. 



intermaxillary bones are of much smaller size. 

 The form of the bony aperture of the nostrils 

 (c,fg. 247) in both the Dugong and Manatee is 

 a large oval, which in the Dugong, as in the 

 typical Cetaceans, is directed upwards. The 

 entire cranium, and especially the frontal bones 



