4i6 



MANUAL OF ELEMENTARY ZOOLOGY 



and a pectoral. The jugulars anastomose under the base 

 of the skull. The inferior vena cava arises by the junction 

 of two iliac veins in front of the kidney. Each iliac 

 vein is formed by the union of a femoral, a renal, and a 

 big hypogastric which passes upwards through the kidney. 

 Behind the kidneys the hypogastrics arise in the following 

 way : The little caudal vein forks into two branches, each 

 of which runs through one of the kidneys as a hypo- 



Fig. 306. — The brain of a pigeon. — From Thomson. 



(1) D0rs.1l, (2) ventral, and (3) side view, c, Cerebral hemi- 

 spheres ; cb., cerebellum ; 111.0., medulla oblongata ; o.l., optic 

 lobes; olf., olfactory lobes ; s.c, spinal cord. 



gastric. Each hypogastric is much larger than the caudal 

 of which it is a branch, because at the bifurcation 

 another vein, the coccygeo-mesenteric from the cloaca 

 and large intestine, joins the caudal, and immediately 

 after it has separated from its fellow the hypogastric 

 receives an internal iliac vein. In its course through 

 the kidney it receives several small renal veins and a 

 sciatic. There is practically no renal portal system, 

 though the femorals give a few small branches to the 

 kidneys. A hepatic portal system exists as usual. A 



