At the point where the dorsal aorta is formed, note the large cceliaco-
mesenteric artery which arises there, and which sends branches to the stomach,
liver, intestine, and spleen. 2

Trace the dorsal aorta backwards, and note that it passes between the
kidneys, there gives off four or six renal arteries, and then divides posteriorly
into two iliac arteries which supply the legs. The iliac artery is continued
backwards as the sciatic artery in each leg, and divides above the knee into the
peroneal and the tibial artery to leg and foot respectively.
3. Trace the pulmo-cutaneous arch, which gives off :—


(a) A pulmonary artery along the outer side of the whole length of the lung.
(b) A cutaneous artery, which passes forward close behind the ear, and then
turns sharply backwards to supply the skin of the back and the sides
of the head.
210 THE FROG—THE PLATANA


[In the Platana—

1. The carotid arch gives off:

(a) Two arteries having a common point of origin near the carotid gland.
One supplies the floor of the lower jaw, and may therefore be called the
“lingual” artery ; the other supplies the mylo-hyoid muscle.
(b) A carotid artery passing to the head. It has, at its origin, a slight swelling,

the carotid gland.
2. The systemic arches run backwards on each side of the body, meeting
posteriorly to form the dorsal aorta. From each systemic arch an artery arises
which has the following branches :—

(i) A scapular artery to the pectoral girdle.
(ii) A cutaneous artery to the skin.
(iii) A brachial artery to the arm.
