230 THE ORGANIZATION 



resolved at a glance. In the Lancelet, and in all fishes, and 

 even in the lower grades of reptiles or reptilian fishes, (Lepi- 

 dosiren, chap, xvi.,) the head is not distinctly separated from the 

 body ; but, as we ascend the scale, through the groups of the 

 higher reptiles, (Lizards, Turtles, &c.,) birds, and finally the 

 warm-blooded vertebrates, Mammals, (figs. 26, 134,) the process 

 of cephalization becomes more and more clearly marked by an 

 external configuration, and within the head by a concentration 

 of the regions of the brain, and the growing preponderance of 

 the divisions devoted to the more delicate sensations of sight 

 and reasoning. 



ut 0v fl r I- k l p ra dp a ao nr v g sk cr au en o 



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

 Fig. 134. 



Mammalia. The body of the higher Vertebrates is divided 

 into head, chest, and abdomen ; the first contains the brain (fig. 



Fig. 134. 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 ; t 1 , end of i ; Iv, liver ; p, 

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

 capsules ; ur, outlet of k ; bl, 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 (ut) ; vg, the vagina, or outlet of ut; 

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



