64 



Cetacea. 



Sirenia. 



Pier-case, 

 No. 21. 



cast of the entire skeleton and a large series of separate bones 

 are exhibited. The cast of a nearly perfect skull of Halitherhtm 

 (Felsinotheriuiii) Forestii (Capellini), from Bologna, is also in the 

 Pier-case, together with the skull and lower jaw of Provost omus 

 sirenoides (Owen), from the Tertiary of Jamaica; a cast of the 

 skull of Halitherium Canhami (Flower), from the Suffolk Crag; 

 and the natural cast of the brain of Mofherium cegypiiacum 

 (Owen), from Mokattam Quarries, near Cairo, together with 

 recent skulls of the African Manatee and the Australian Dugong 

 placed for comparison with the fossil forms. 



Order VIII.— CETACEA (Whales). 



Table-case, 

 No. 1 1, and 

 Wall-cases, 

 Nos. 22 

 and 28. 



In this order of the Mammalia the body is still more fish- 

 like than in the Sirenia. There is no trace of a neck, the 

 contour of the head passing gradually into that of the body. 

 They have a horizontally flattened caudal fin and very generally 

 a median dorsal fin also. 



The anterior limbs alone are present externally, and these 

 are not divided into arm, fore-arm, and hand, but they form 

 a broad flattened paddle without any trace of nails. The 

 cervical vertebras in many species of Cetacea are more or less 

 fused together into a solid mass. None of the vertebras are 

 united together to form a sacrum. The pelvis is quite 

 rudimentary, as are the hind-limbs when present. 



Fig. 75. — A, molar tooth; B, caudal vertebra (reduced) of Zeuglodon cetoidcs (Owen), 

 Middle Eocene, Alabama, U.S., .North America. 



Teeth are generally present, but they are exceedingly 

 variable in number. 



In one group, the Mystacoceti, teeth are quite absent, save in 

 the foetal state, the palate being provided with numerous 

 transversely-placed homy laminae, termed "baleen."* 



* The "whale-bone" of commerce. 



