ANIMAL BIOLOGY. 



[Part I. 



mesenteric, p. in. a.). A large sciatic artery (sc. a.) passes through 

 the kidney on each side, and gives off branches to that organ, 

 which is also supplied with arterial blood by an anterior branch 



pul.cir 



FIG. 21. CIRCULATION OF PIGEON. 



springing directly from the aorta. Posteriorly the aorta splits 

 up into four branches, one median (caudal, c.) ; one median and 

 ventral, the posterior mesenteric (p. m. a.) ; and one on each side 

 (hypogasfaic, hyp. ). 



The blood from the stomach and intestines is delivered to the 

 liver by a portal vein, and thence passes by hepatic veins into the 

 postcaval (pt. c.). This postcaval results from the confluence of 

 two large iliac factors (il. v.), which receive blood from the hind 

 limbs by the large crural veins (cr. r.). Where the crural vein 



