THE AMERICAN NATURALIST. [Vol. XXXVII. 



common iliac vein nearly opposite the point at which the 

 superior gluteal branch of the internal iliac artery in given off, 

 and through this slit the superior gluteal artery passes. This 

 artery arises much farther cephalad than the left superior 

 gluteal ; the latter is in the normal position. The corresponding 

 veins, on the other hand, arise symmetrically from the dorsal 

 surface of the two common iliac veins. The opening does not 

 divide the vein into tubes of equal diameter, that on the median 

 side being much broader than the tube on the outside, but the 

 1 cn s terrupted on both sides of the slit. 



Abnormalities in the vessels in this region are very frequent 

 in the cat, and this same specimen shows one or two others. 

 Thus while the right umbilical artery leaves the internal iliac at 

 the usual point the left comes off much farther caudad than is 

 customary and is much smaller than the right. The median 

 sacral vein arises from the right common iliac instead of the left, 

 an abnormality which has frequently been observed. In other 

 respects, however, the vessels in this region of the cat in question 



