VEETEBRATE8. 
135 
veins, a system of capillary vessels, which are minute tubes 
connecting the ends of the smaller arteries with the smaller 
veins. There are no genuine capillaries in the lower ani- 
mals exactly comparable with those of vertebrates. 
The blood is red in all the vertebrates except the lance- 
let, and besides white corpuscles contains red corpuscles. 
While fishes and tadpoles breathe by gills, all land and am- 
phibious vertebrates breathe the air directly by lungs con- 
nected by a windpipe (trachea) with the mouth. The 
nervous system consists of a brain and spinal cord. The 
brain consists of four pair3 of lobes, i.e., the olfactory 
Fig. 176.— a diagrammatic section across the body in the chest region, x. the 
dorsal tube, which contains the spinal cord; the black mass surrounding: it is 
a vertebra ; a, the gullet, a part of the ah' mentary canal; h, the heart; ay, 
sympathetic nervous system ; 1 1, lungs; the dotted lines around them are the 
pleurae; rr, ribs; st, the breastbone. From Martin. 
lobes, cerebral hemispheres, the optic thalami with the 
pineal gland, and the optic lobes; besides these lobes, which 
are arranged in pairs, there are two single parts of the 
brain, the cerebellum and the beginning of the spinal cord, 
called the medulla ollongata. 
The limbs each consist of a single long bone, succeeded 
by two long bones, followed by two transverse rows of 
short wrist or ankle bones, and five series of long finger or 
toe bones called phalanges. For example, in the fore limb 
of most vertebrates, as in the arm of man, to the shoulder 
girdle is articulated the humerus; this is succeeded by the 
ulna and radius; these by the wrist-bones or carpals, and 
r 
