AND PHYSIOLOGY. 



91 



Fig. 101. Pig. 102. 



Teeth of an Herbivorous Animal. Teeth of an Insectivorous Animal. 



and nether millstone for grinding grain. Those which live 

 upon small insects have conical teeth with corresponding de- 

 pressions in the opposite jaw in order to crush the skeletons 

 and envelops of their prey. The Seals, which live on Fish, 

 are provided with barblike appendages similar to those on fish- 

 hooks, in order that they may hold their slippery prey. 



199. Humerus, in Burrowing Animals. — The Humerus 

 is generally a long cylindrical tube, with a large rounded 

 head at its upper extremity. But in swimming and burrow- 

 ing animals it is a short and curved bone, with each extrem- 

 ity very much modified for the attachment of muscles, since 

 the fore-legs of such animals need to be used with great fre- 

 quency and force. 



200. Bones of Fore-Arm. Carpus, Metacarpus, Pha- 

 langes. — The element in which mammals live, greatly modi- 

 fies the bones of the fore-arm and hand. (Fig. 103, p. 92.) 

 In general there are two bones in the fore-arm, and but few 

 animals have the power to move these one upon another like 

 man. The Carpus is constantly made up of two rows, though 

 not of the same number. They vary from five to eleven. The 

 Metacarpus consists of five elongated bones for the most part. 

 But these are three in the Rhinoceros, and one with two 



What is remarkable about the teeth of the Seal ? 199. What is the general outline of 

 the Humerus? In what animals is it modified ? 200. What effect has the element, in 

 which animals live, upon the anterior extremities? How do the Carpal Bones range in 

 number? AVhat are the exceptions to the typical number five of the Metacarpus? 



