20 CHARLES F. W. McCLURE AND GEORGE S. HUNTINGTON 



from an elongation of the right side of the renal collar (Siibc. 

 Sprc.Anast.). The changes brought about by this elongation 

 can easily be seen in those figures in our joint paper which 

 illustrate the development of the renal collar (Huntington 

 and McGlure, '20, figs. 8, 9, 10, and 11). Especially in figure 

 11 (H. and McC.) is clearly demonstrated the relation that 

 exists between the elongated renal collar and the right sex 

 vein (posterior cardinal). 



An examination of a number of examples of Type AB in the 

 cat has shown that the caudal extent of the periureteric ve- 

 nous ring varies in individual cases, extending caudad, as in 

 figure 9, to the iliolumbar veins or, as in figure 10, only to a 

 point somewhat craniad of this level. Differences in the 

 caudal extent of the venous ring are dependent upon the 

 extent to which either the right posterior cardinal or the right 

 lumbar supracardinal vein may be involved in the ring's for- 

 mation. When practically the entire right lumbar supracar- 

 dinal vein persists, the venous ring extends caudad to the 

 iliolumbar level (fig. 9). When only a portion of the right 

 lumbar supracardinal vein persists, the caudal extent of the 

 ring is determined by the level at which, cranial to the ilio- 

 lumbar level, an anastomosis (Pc. Sprc.Anast., fig. 1) is re- 

 tained between the right posterior cardinal and the right 

 supracardinal veins. 



Type AB was found by Darrach in only three, or 0.5 per 

 cent, of the adult cats examined. It was described for the 

 cat by Gage in 1898; but, so far as we know, has been ob- 

 served in man only by Wicke ( '27 ) 6 and possibly by Melissi- 

 nos in a doubtful case figured by him in 1911. 



* This case described by Wieke is a most unusual one. In addition to the 

 presence of a right periureteric venous ring (Type AB), the left common iliac 

 vein passes ventral, instead of dorsal, to the right common iliac artery, indicating 

 the persistence of a channel derived from the cardinal collateral vein (C.C. in 

 fig. 1). See figure 63, plate XLVI. 



