CETACEA. 565 



In one large group no teeth occur, except in the foetus ; when 

 teeth are present after birth, all are similar in form, and are not 

 preceded by milk-teeth. 



By far the majority of Cetacea are marine, but many enter large 

 rivers, and a few are restricted to them. All are carnivorous and 

 live on fish, Crustacea, or mollusca ; one genus, Orca, preying on 

 seals and whales. Like other mammals, cetaceans are air-breathers 

 and come to the surface of the water to breathe or " blow." The 

 old idea, represented in many pictures, that whales " spout " or 

 eject by the blow-holes water taken in by the mouth, is erroneous, 

 the supposed jet being merely the expired air with watery and 

 mucous particles forming spray. The " spouting " is naturally 

 much more conspicuous in cold regions. The acts of expiration 

 and inspiration are very quickly performed, especially by dolphins. 



The order is divided into two suborders thus defined : 



No teeth after birth ; baleen present. Breathing- 

 orifice double MYSTACOCCETI. 



Teeth present throughout life ; no baleen. 



Breathing-orifice single ODOOTOCCETI. 



In the preparation of the following account of Indian cetaceans, 

 I have generally followed Prof. W. H. Flower, to whom I am 

 indebted for much personal aid, in addition to the information 

 published in his papers on various genera of the order. 



Suborder MYSTACOC(ETI. 



Teeth never present after birth. The palate is furnished with 

 numerous plates of baleen or whalebone, serving to strain the 

 water from the fish, Crustacea, or mollusca, mostly of small size, on 

 which whales feed. Skull symmetrical. Kami of mandible arched 

 outwards, not uniting in a true symphysis at the distal extremities. 

 Bdbs very loosely connected with the vertebrae, and articulating 

 only with their transverse processes ; the first rib alone connected 

 with the sternum. External openings of the two nostrils separate, 

 longitudinal. A caecum present. 



Family 



Characters of the suborder, of which this is the only family. 

 The principal genera are the Eight Whales (Balcena), with enor- 

 mous heads, long baleen, no dorsal fin, and united cervical 

 vertebrse, and the Humpbacks (Megaptera) and Fin-whales or 

 Rorquals (Balcenoptera)^ with smaller heads, shorter baleen, a 

 dorsal fin, and free cervicals. Only the last-named genus has 

 been as yet clearly recorded from Indian seas. 



