The President's Address. By Dr. H. Woodward. 155 



from teeth, being produced from the ephithelium, the cuticular 

 covering of the lips. 



Sirenia. — The Sirenia form an entirely distinct group of re- 

 markable aquatic vegetable-feeding animals, subsisting entirely on 

 the aquatic plants in rivers, and on the great beds of laminaria 

 and other sea-weeds, which grow just below low-water and 

 especially abound in the North Pacific Ocean. Numerous species 

 formerly existed in the Old World whose remains are met with in 

 Eocene, Miocene, and Pliocene strata in Europe, North Africa, in 

 our own Crag formation, as well as in that of Antwerp. One 

 huge form, about 20 ft. in length, known as " Steller's sea-cow," 

 Rhytina f/igas, was living on the coast of Behring and Copper 

 Island, off Kamchatka, between 1740 and 1780, but it was en- 

 tirely exterminated by the hand of man. The adult animal was 

 apparently edentulous (the young only being furnished with milk- 

 teeth) ; instead of teeth there were horny palates on the upper and 

 lower surface of the mouth, which, being strongly ribbed trans- 

 versely, served in place of teeth. Two other surviving forms : 

 one, the Manatee, inhabiting the shores and rivers of both sides of 

 the Atlantic, near the line of the equator, and met with in the 

 Congo in Africa, and the Amazons and Orinoco in South America ; 

 the other species, the Dugong {Halicore), being confined to the 

 shores and islands of the Indian Ocean, the Bed Sea, and the 

 eastern shores and northern coasts of Australia. Both these forms, 

 being restricted to those localities where sea- weeds and other aquatic 

 plants abound, on which they feed, are rapidly being exterminated 

 by man. Some years ago a company was formed on the east coast 

 of Australia for the production of dugong oil ; so that the Halicore 

 australis will soon be a thing of the past. 



No doubt these forms were at one time derived from terrestrial 

 ancestors. The teeth in the Manatee are tuberculated molars 

 resembling those of the pig and the hippopotamus. The teeth in 

 the Dugong are of a more simple form and fewer in number. The 

 Ehytina, as before stated, had no teeth. The hind limbs in all 

 these Sirenians are only indicated by & rudiment within the body 

 as is also the case in the Cetacea. The Sirenians retain free move- 

 ments of the bones of the fore-arm, with separate motion between 

 the humerus and the radius and ulna, which is lost in the Cetaceans, 

 the whole fore-arm being rigid, moving only from the shoulder, 

 thus forming a true flipper or fin. 



Although owing to their mode of life these two groups are 

 purely aquatic in habit, yet they possess all the attributes of the 

 mammalian class. They bring forth their young alive ; they are 

 nourished by the milk of the parent, and the offspring enjoy the 

 same tender care from the mother as do the young of terrestrial 

 animals. 



Edentata. — The Edentata are not all toothless animals, as their 



m 2 



