UNGULATA. 57S 



cleft. There are retia mirabilia on the arteries. The 

 testes are abdominal in position. The uterus is bicornuate. 

 Two teats lie behind the arm-pits. The placenta of the 

 dugong is zonary, wholly or in great part non-deciduate. 



Manatee {Manatus). Dugong {Halicore). 



Neck vertebrae reduced to six. The usual seven neck vertebrae. 



Abortive incisors ( |) in both sexes. Two tusk-like incisors persist in 



the male. 



Molars (}^, six or so at a time) ; Molars (f or f, 2 or 3 at a time), 

 uniform, with square enamelled primitive, with persistent pulps 

 crowns, and tuberculated, and no enamel, 

 transverse, grinding ridges. 



Premaxillae almost straight. Premaxillse crooked downwards. 



Tail rounded. Deeply notched tail. 



Rudimentary nails on fingers. Nail-less digits. 



Caecum divided. Thick and single c!ecum. 



M. australis and M. senegalensis H. tabernaculi, E. African coast 

 live in the mouths of great rivers and Red Sea ; ^. dugong, Indian 

 which flow into the tropical At- and Pacific Oceans eastward 

 lantic. from the home of the last species 



to the Philippines ; H. australis, 

 E. and N. Australia. 



The genus Rhytina was toothless, with a slightly crooked snout, 

 small head and arms, and thick naked skin. Steller's Sea-Cow 

 {R. stelleri), the only known species, from the north Pacific, seems to 

 have been exterminated in the last century. 



The order was once much larger. Fossil forms occur in Tertiary 

 strata. The most important is Halitherium, a less specialised Sirenian 

 than those still extant, and with at least traces of hind-limbs. 



Order 3. Ungulata. 



• Hoofed Animals — Artiodactyla, Perissodactyla, Hyra- 

 coidea, Proboscidea, and extinct sub-orders. 



This large and somewhat heterogeneous order includes 

 pigs, hippopotamus, camels, cattle, deer, tapirs, rhinoceros, 

 horses, hyrax, elephants, and some other distinct types. 



They are terrestrial, a,nd for the most part herbivorous 

 animals. Their digits generally end in hoofs or at least in 

 broad nails. In the adults of the modern types there are no 

 clavicles. The teeth are diverse and of two sets, the milk 

 set in part persistent until the animal attains maturity. 



