CLASS MAMMALIA 645 



Order 12. Proboscidea. ELEPHANTS. UNGULATA with 

 long, prehensile proboscis ; incisors form tusks; 

 molars very broad. Examples: Elephas, Asiatic ele- 

 phant; Loxodonta, African elephant (Fig. 540). 



Order 13. Sirenia. SEA-COWS. Aquatic EUTHERIA of 

 the ungulate type; tail with horizontal fin; fore limbs 

 fin-like; hind limbs absent. Examples: Halicore, 

 dugong; Manatus, manatee (Fig. 541). 



Order 14. Hyracoidea. HYRACES OR CONEYS. Small ro- 

 dent-like mammals, with short ears and reduced tail; 

 fore limbs with four digits; hind limbs with three digits. 

 There is a single living genus, Procavia, and about 

 eighteen species, in Africa. One species, P. syriaca, 

 reaches Syria; it is the coney of the Bible.. 

 Section D. CETACEA. WHALES AND DOLPHINS. Aquatic 

 mammals probably derived from the UNGUICULATA or 

 UNGULATA. 



Order 15. Odontoceti (DENTICETI). TOOTHED WHALES. 

 CETACEA with teeth, at least on the lower jaw; no 

 whalebone. Examples : Delphinus, dolphin (Fig. 542) ; 

 Phoccena, porpoise; Grampus, grampus. 



Order 16. Mystacoceti. WHALEBONE WHALES. CETACEA 

 without teeth in adult; mouth provided with plates 

 of whalebone. Examples: Balanoptera, fin whale; 

 Balcena, right whale. 



3. A REVIEW OF THE PRINCIPAL ORDERS AND FAMILIES OF 

 LIVING MAMMALS 



Order Monotremata. EGG-LAYING MAMMALS. The MONO- 

 TREMES are primitive mammals confined to Australia, New 

 Guinea, and Tasmania. Their most conspicuous peculiarity is 

 their egg-laying habit, since they are the only mammals that 

 reproduce in this way. The two oviducts do not unite to form 

 a vagina, but open into a cloaca along with the intestine and 

 urethra, as in birds and reptiles (hence the term Monotremata: 



