118 THE CLASSIFICATION OF CUVIER. 



run in order to form a connection with each other. On the 

 other hand, Cuvier seemed to believe, (I say seemed to believe, 

 because he speaks of certain groups, the Barnacles for instance, 

 as establishing, " by several relations, a sort of intermediary 

 between " the Mollusca and the Articulata,) his four groups to 

 be four distinct types, or ideas. 



Thus, he says, the Vertebrata are principally characterized by 

 having "the brain (fig. 51, en, cr) and the principal trunk (nr) of 



vg ut ov f. ur k k 1 p va dp a ao nr v g sk cr au en 



mm 01 i s st Iv I vc h la ao 1 

 Fig. 51. 



the nervous system enclosed in a bony envelop, which consists of 

 a skull (sk) and a vertebral column (v, va), or backbone." 



The Mollusca, commonly called shell-fish, " have no skeleton; 

 the nervous system, which consists of several scattered masses 



Fig. 51. A diagramic longitudinal section of a Mammal, sk, skull; v. ver- 

 tebrae ; a, dorsal arches of the vertebras ; va, the upper and lower portions of the 

 vertebral arch ; j, lower jaw ; b, bone of the leg ; m, muscle ; d, teeth ; t, tongue ; 

 g, gullet ; *, thyroid gland ; st, stomach ; i, intestine ; i 1 , end of i ; Iv, liver ; p, 

 pancreas ; s, spleen ; k, kidneys ; k 1 , appendages to k, known as the suprarenal 

 capsules ; ur, outlet of k ; U, bladder ; e, epiglottis, or entrance to the wind- 

 pipe (f) ; /, lung; h, heart; ao, abdominal aorta; ao 1 , carotid artery going to 

 the head ; vc, vena cava inferior, or abdominal vein ; la, pulmonic artery ; dp, 

 diaphragm ; o, the eye ; en, cerebrum ; cr, cerebellum ; n, olfactory nerve ; au, 

 the outer ear ; nr, spinal marrow, or main nervous cord ; ov, the ovary, or egg- 

 bearing portion of the reproductive organ ; fl, the trumpet-shaped Fallopian tube 

 through which the eggs pass into the uterus (ul) ; vg, the vagina, or outlet of ut; 

 mm, the mammas, or milk-bag. From Owen. Slightly altered. 



