20 VERTEBRATES. 



after the same general plan, changed, however, and modified in 

 certain parts or organs, to fit them for the stations which they are 

 designed to occupy. (See Plates III. and XII.) All of them are 

 viviparous, (born alive.) The young, as the name of the class 

 denotes, are, for a longer or shorter time, nourished by the milk 

 of the mother. Sometimes they are born with their eyes open, 

 and able immediately to move about and seek their own food ; 

 hut not a few of them are born with their eyes closed, and 

 in a state of extreme helplessness. 



The leading characters of the Mammalia are founded on the 

 number and kind of their teeth, (see Plate IV.) and the construc- 

 tion of their hands and feet. (See Plates III. and VI.) The 

 expertness of these animals is closely connected with the per- 

 fection of the organs of touch. The nature of their food and 

 their digestive functions may, in great part, be inferred from the 

 number and structure of their teeth. (See Plates III. and VI.) 



They are divided into three sub-classes, viz. : UNGULATA, (lat. 

 ungula, a hoof,) animals with hoofs ; and UNGUICULATA, (lat. 

 Uiiguiculus, a soft, small nail.) animals with nails or claws ; and 

 CETACEA, with fins, (Gr. Ketos,) a whale, or sea monster. 



The Mammals are, (on the Chart.) arranged into nine orders, 

 after the plan of Cuvier, that arrangement being deemed, on the 

 whole, the most satisfactory The number of well established 

 species, according to Dr. Hitchcock, is somewhat more than 

 2000. 



The names of the nine orders are, I. BIMANA ; II. QUAD- 

 RUM ANA ; III. CARNIVORA; IV. MARSUPIALIA; V. EDENTATA; 

 VI. RODENTIA; VII. PACHYDERMATA ; VIII. RUMINANTIA ; IX. 

 CETACEA. 



Some naturalists have elevated the CHEIROPTERA, the INSEC- 

 TIVORA, and the MONOTREMATA to the rank of orders, making the 

 number XII ; but the first two of these are flesh-eaters, and 

 therefore properly included among the Carnivora, (or the Carnas- 

 siers of Cuvier;) and the MONOTREMES, including but two gen- 

 era, have such points of resemblance to the MARSUPIALIA, as 

 justify referring them to that order. 



QUESTIONS ON THE VERTEBRATES. 



What is the first class of Vertebrates? Who first used the term ? Who 

 was Linnaeus ? Ans. An eminent Swedish naturalist. He was the author 

 of the Linnaean, or artificial system of Botany. What does the term 

 Mammals, or Mammalia designate? What position in the ANIMAL 

 KINGDOM does this class occupy? Of what beings is it composed? 

 For what are a large part of the Mammals formed? How do others 

 of this class live and move? What is said of their skeletons? Are 



