254 VERTEBRA.TA. 



Order X. CETACEA. 

 NATANTIA. MUTILATA. 



Fish-like ; nostrils (spiracles) on the top of the head. Fore 

 limbs only, fin-like and without nails. No sacrum. Pelvis 

 rudimentary. A horizontal tail-fin without bony rays. 



The Cetacea differ from all other mammals in having the 

 nostrils, or blowholes, placed on the top of the head, and, except- 

 ing Sirenia, in having a horizontal tail-fin, not supported by bony 

 rays. A few species have a dorsal fin. By some they are supposed 

 to be modified Ungulata, by others modified Carnivora (Pinni- 

 pedia). 



There are no external ears. The body is sparsely hairy, or it 

 may be without hairs in the adult. There are no clavicles, and 

 sometimes there are no teeth except in the foetus. The dolphins 

 have from 100 to 200 teeth. In the male narwhal a tusk is 

 developed in the left premaxillary bone often attaining the length 

 of ten feet ; on the right and in the female the germ-cavities are 

 gradually enclosed by the forward growth of the bone. The two 

 mammae are inguinal. The placenta is diffused. To the palate 

 are attached certain plates, or baleen ; as many as 302 rows on 

 either side have been counted in the " right " whale [Eschricht]. 

 From these are derived the whalebone of commerce. Their use 

 is to retain the small animals on which the creature lives, until, 

 having collected a sufficient quantity, they are swallowed, the 

 water either making its escape at the sides or being ejected through 

 the blowhole. The stomach is complex, divided into three or 

 four cavities in all true Cetacea. Two little detached bones, 

 placed near the anus, are the only vestiges of the posterior 

 extremities. 



Spermaceti is a fatty secretion found in cells in the upper part 

 of the skull of the cachalot, as well as in the blubber. Ambergris 

 is an odorous concretion found in the intestines. 



Among the members of this order are the grampus (Phocana 

 orca), porpoise (Phoc&na communis], dolphin (Delphinus delphis), 

 [the dolphin of sailors is a tropical fish, Coryphcena hippuris], 

 dolphin of the Ganges (Platanista gangetica), dolphin of the 

 Amazon (Inia amazonica), grampus (Orca gladiator], the ca'ing 

 whale oTbott\eu.ose(Globiocephalus globiceps), the finner, rorqual, 

 or fin-whale (Balcenoptcra sibbaldii and B. rostrata], hump-backed 

 whale (Megaptera boops), cachalot or spermaceti whale (Physeter 

 macrocepkalus), right or Greenland whale (Bal&na mysticetus), 

 narwhal (Monodon monoceros), white whale (Beluga leucas]. 



