1914.] NATURAL SCIENCES OF PHILADELPHIA. 419 



artery, m^, which is given off in about the region of the fourth pair 

 of lumbars; it carries blood through the mesentery to the greater 

 part of the small intestine and also sends a small branch to the 

 large intestine. 



Posterior to the mesenteric, the aorta gives off four or five pairs 

 of short arteries, the urogenitals, u 1-4, that lead to the nearby 

 reproductive organs and kidneys. 



About the middle region of the kidneys, a short distance anterior 

 to the sacrum, is given off a pair of rather large arteries, called by 

 Bronn the ischiadicce, is^; each ischiadica, after giving off a couple 

 of small branches to the back, passes laterad and divides into three 

 main branches: (P) to the ventral body wall, (3^) to the anterior 

 border and deeper region of the thigh, and (2^) to the pelvis. 



In the region of the sacrum is given off a pair of iliac arteries, il^ 

 Each iliac is of about the same diameter as the ischiadica and gives 

 off, soon after leaving the aorta, an artery, ab, that apparently leads 

 chiefly to the abdominal muscles. Distal to the origin of the abdomi- 

 nal, the iliac gives off a small pelvic artery, pa, which leads, as the 

 name would indicate, to the pelvis. The iliac then passes into the 

 thigh, where it gives off several large branches and may be called 

 the sciatic, sc. At the knee the sciatic gives off two rather small 

 branches, one, the fibular artery, f ^ extends down along the posterior 

 side of the lower leg; the other is parallel to the first and may be 

 called the tibial artery, tb, since it extends along the anterior or 

 tibial side of the shank. These two arteries give off numerous 

 branches to the muscles of the lower leg. After giving off the fibular 

 and tibial arteries, the sciatic passes, as a large vessel, through the 

 lower leg, to which it gives but few branches, and may here be 

 called the crural artery, cr. At the tarsus it divides rather suddenly 

 and, perhaps, variably, into four chief branches, leading to the 

 toes. 



A short distance caudad to the origin of the iliacs the dorsal aorta 

 gives off a pair of small pelvic arteries, pa^ going to the muscles of 

 that region. Caudal to these pelvis arteries is given off the un- 

 paired first hcemorrhoidal artery, he\ which divides into a rectal, rt^, 

 and a cloacal, cl, branch. 



Caudal to the first hsemorrhoidal arises the second hcemorrhoidal, 

 he^; also unpaired, leading to the cloaca. 



Posterior to the second haemorrhoidal, the aorta continues into 

 the tail as the large caudal artery, ca. 



28 



