XIII.] THE FROG. 171 



B. Veins. 



1. The system of the superior cava formed on each 

 side by the union of the vena innominata, the sub- 

 clavian and the external jugular. 



a. Internal jugular vein : leaves the skull by the 

 jugular foramen, and brings back blood from 

 the brain, spinal cord and anterior vertebral 

 region. 



b. Subscapular: returns the blood from the brachium 

 and shoulder. These two veins (a and 6) unite to 

 form the vena innominata. 



c. The musculo-cutaneous vein, receiving the blood of 

 the surface of the head (except the mandibular 

 and hyoidean regions) and that of the back of 

 the trunk passes forwards between the internal 

 and external oblique muscles of the abdomen. 



d. The brachial vein receives blood from the ante- 

 brachium and manus. 



These (c and d) unite to form the subclavian vein. 



e. The veins of the mandibular region and those 

 of the tongue unite into the external jugular 

 vein. 



2. The system of the inferior cava, formed by the union 

 of the renal, genital and hepatic veins. 



a. The femoral vein from the front of the leg, 

 and 



b. The sciatic vein from the back of the leg, pour 

 their blood into a trunk which lies in the lateral 

 wall of the pelvis and may be termed the pelvic 

 vein ; the dorsal end of this becomes 



