30 THE VASCULAR SYSTEM OF THE FROG. 
III, The Pulmo-cutaneous Arch (the fifth embryonic arch) : 
the hindmost of the three persistent arches: it divides 
about the level of the carotid gland into :— 
1. The cutaneous artery: a large artery which at first 
runs forwards and upwards and then turns backwards, 
supplying the skin of the back along the whole length 
of the body, and sending smaller branches to the sides 
of the head and the skin of the ventral surface. 
2. The pulmonary artery: runs in a somewhat sinuous 
manner along the outer side of the whole length of 
the lung, giving off branches into its substance. 
D. The Structure of the Heart, 
Fig. 6. The frog’s heart seen from the ventral surface, and dissected so 
