24 CHARLES F. W. McCLUEE AND GEORGE S. HUNTINGTON 



joins the right cava (posterior cardinal) dorsal to the aorta, 

 at a point somewhat caudal to the level of the renal veins. 

 In the third case (fig. 16) the left para-aortic axial vein 

 extends as a continuous vessel between the left iliolumbar 

 and the left renal veins, and at about its caudal third receives 

 the left spermatic vein, which in figures 14 and 15 opens into 

 the left renal vein. In all three cases mentioned, the left 

 ureter extends from the kidney to the bladder, without pass- 

 ing between the aorta and the left para-aortic axial vein. 

 One may therefore interpret the left para-aortic axial vein in 

 figures 14, 15, and 16 as due to the persistence in part (figs. 

 14 and 15), or in whole (fig. 16), of the left lumbar embryonic 

 supracardinal vein. In figure 14 the caudal fifth, in figure 15 

 the caudal two-thirds, and in figure 16 the entire embryonic 

 lumbar supracardinal vein have been retained. The connec- 

 tion, dorsal to the aorta, which the left para-aortic axial vein 

 makes with the right cava in figures 14 and 15 is due to the 

 persistence of anastomoses which, at different levels, exist in 

 early stages between the left supracardinal and the right pos- 

 terior cardinal veins (Int.Sprc.Anast. and Pc.Sprc.Anast., 



fig.'l). 



Type AC in the cat was first described by Gage in 1898. 

 It was found in only four of the 605 cats examined by Dar- 

 rach. We know of no instance in which Type AC has been 

 found in man. 



7. Persistence of right posterior cardinal, left supracardinal, 

 and left posterior cardinal veins. Left periureteric 

 venous ring present, through which ureter passes 



Type ACD (A, C, and D in fig. 1). Figure 17, cat (Metcalf, '18) 



Figure 17 is a photograph of Type ACD, described and 

 figured by Metcalf as occurring in an adult cat. So far as 

 we could determine, this variant marks the only instance on 

 record in which Type ACD has been either observed or de- 

 scribed as occurring in the adult cat or in any other mammal. 

 Also, with the exception of Erinaceus europaeus, described 

 by Hochstetter ('93), the case figured by Metcalf is the only 



