PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 395 



in the popliteal space and eaters the femoral veiu. There is no 

 upward vein running through a saphenous opening, and that 

 opening is a human characteristic. 



Two venfe comites accompany all the branches of the posterior 

 tibial artery. They unite to form one popliteal vein which 

 accompanies the artery and becomes the femoral vein. The 

 venous circulation closely follows the arterial supply, but no 

 epigastric vein enters the femoral. The saphenous veins open, 

 as described above, into the popliteal and femoral veins. 



The veiyis of the peli-is follow the branches of the hypogastric 

 artery, and the hi/pogastric vein joins with the external iliac 

 vein to join the common iliac vein. The two common iliac veins 

 unite to form the vena cava inferior. These veins have rela- 

 tions similar to those in Man. 



Veins of the Pectoral Extremity. 



The venous circulation differs in several points from that in 

 Man. The veins of the hand unite to form the cephalic vein 

 which only extends up as far as the antecubital fossa. Thei-e 

 it dips inwards and unites with venae comites following the 

 branches of the brachial artery to form the brachial vein. No 

 basilic vein is present. The brachial vein runs upwards, re- 

 ceiving tributaries corresponding to the branches of the artery. 

 It is successively followed by the axillary and subclavian veins 

 which receive tributaries corresponding to the branches of the 

 arteries. The subclavian veins unite with the external jugular 

 veins to form the innominate veins. The venous circulation 

 differs from that of Man in the shortness of the cephalic vein, 

 the absence of the basilic vein, the presence of a brachial vein 

 instead of venfe comites, and the absence of an internal jugular 

 vein uniting with the innominate vein. 



The Ductless Glands. 



The thyroid gland (text-fig. 41) is long, narrow, and thin. 

 The lateral lobes are bent on themselves at the upper ends, 

 which lie against the cricoid and lower end of the thyroid 

 cartilage. The thicker isthmus crosses the fourth and fifth 

 tracheal rings. There is no strong capsule and no pyramidal 

 lobe. It receives a complicatel series of arterial anastomoses 

 from the superior (S.T.A), middle (M.T.A), and inferior (I.T.A) 

 branches of the external and common carotids, and the thyroidea 

 ima (T.I.A) from the left common carotid. Xo subclavian 

 branches pa&s to the gland. The superior th}T:oid vein (S.T.Y) 

 opens into the anterior facial vein, and the inferior thyroid vein 

 (I.T.V) goes to the innominate vein. 



At the lower border of the isthmus there is, on each side, an 

 oval body, the size of a pea, consisting of the parathyroid glaiid 

 and a piece of thymus. Xo other parathyroid tissue was present. 



