MAMMALIAN ORDERS. 



281 



tliough with certain geographical limits as respects species. They 

 feed on fishes or marine animals. Some undoubted Cetacean 

 fossils are of eocene age : and there are indications of the order 

 in the upper oolitic period.^ 



161 



Deutitiou of Dugoug (Halicore). V. 



The second Mutilate order, called Sirenia, have teeth of differ- 

 ent kinds, incisors, i, fig. 160, which are preceded by milk-teeth, 

 d i, and molars, m, with flattened or 

 ridged crowns, adapted for vegetable 

 food. No digit has phalanges in 

 excess of the mammalian number, 

 three. The nostrils are two, situated 

 at the upper part of the snout ; the 

 lips are beset with stiff bristles ; the 

 mamma3 are pectoral; the testes are 

 abdominal, but are associated with 

 vesiculae seminales. The Sirenia 

 exist near coasts or ascend large 

 rivers ; browsing on fuci, water 



plants, or the grass of the shore. The oldest known Sirenian is 

 of miocene age. There is much in the organisation of this order 

 that indicates its affinity to members of the succeeding division. 



In the Ungulata the four limbs are present, but that portion of 

 the toe which touches the ground is incased in a hoof, figs. 162 

 and 163, which blunts its sensibility and deprives the foot of 

 prehensile power. With the limbs restricted to support and 



Molars of lower jaw, African Elci>haiit. 



' XV11I-. pp. XV. 520. 



