MAMMALIA. 27 



of Europe, in the following elementary summary the arrangement 

 of the Regne Animal is chiefly followed. 



The Mammalia are placed at the head of the animal king- 

 dom, not only because it is the class to which man, considered 

 in his animal structure, belongs, but also because the Mammalia 

 enjoy the most numerous faculties, the most delicate sensations, 

 and the most varied powers of motion. As the quantity of re- 

 spiration is in mammiferous animals moderate, they are gene- 

 rally formed for walking, and in consequence, all the articulations 

 of their frame have defined forms which determine their mo- 

 tions. 



Some of the Mammalia, however, can raise themselves in the 

 air by means of elongated limbs connected by extensible mem- 

 branes ; others have their limbs so much shortened that they 

 can move with facility only in water ; but these circumstances 

 by no means exclude them from the class to which they are 

 allied by other essential characters. 



All the Mammalia have the upper jaw fixed to the cranium ; 

 the lower is composed of two pieces articulated by a projecting 

 condyle to a fixed temporal bone. The neck is composed of 

 seven, and in one species of nine vertebrae. The anterior ribs 

 are attached to a sternum, formed of a number of pieces, placed 

 vertically. Their anterior extremity commences at the scapula, 

 which is not articulated to any other bone, but simply suspend- 

 ed in the muscular attachments, and often resting on the ster- 

 num by an intermediate bone, denominated the clavicle. This 

 extremity is. continued by an arm, a fore-arm, and a hand, which 

 last is formed of two rows of little bones called the carpus, of 

 another row named the metacarpus, and of fingers, each com- 

 posed of two or three bones called phalanges. 



With the exception of the Cetacea, all this class have the 

 first part of the posterior extremity fixed to the spine. This 

 part, in the form of a girdle or basin, is named the pelvis. In 

 youth it is divided into three pairs of bones, the os ilium , which 

 is attached to the vertebral column ; the os pubis, which forms 

 the anterior part; and the ischium, which forms the posterior por- 

 tion. At the junction of these three bones is the cavity where 

 the bone of the thigh is articulated, to which again is joined the 

 leg, composed of two bones, the tibia and ihejibula. This ex- 



