PLATE II 



EXPLANATION OF FIGURES 



2 Keconstruction (after Born) of veins in the lumbar region of a 16-mm. 

 cat embryo. Lateral aspect, right side, showing the right posterior cardinal (A), 

 the right supracardinal (B), the left supracardinal (C), the right periureteric 

 venous ring, through which the ureter (Vr.) passes, and the left side of the 

 renal collar (Siibc.Sprc.Anast.). Princeton Embryological Collection, no. 15. 



3 Eeconstruction (after Born) of veins in the lumbar region of a 16-mm. 

 cat embryo. Lateral aspect, left side, showing the left posterior cardinal (D), 

 which has lost its caudal connection with the left supracardinal (C), so that a 

 periureteric venous ring is not present on the left side. The left posterior 

 cardinal (D), with its subcardinal sex-gland tributaries, forms the left V. sper- 

 matica interna in the adult. The right posterior cardinal (A, fig. 2) similarly 

 forms the vena spermatica of the right side. Note that the posterior cardinals 

 (A and Z>), on either side of the body, joins the caudal border of the lateral 

 portion of the renal collar (Subc.Sprc.Anast.) and that the right and the left 

 supracardinals (B and C) anastomose with each other, dorsal to the aorta, by 

 intersupracardinal anastomoses (Int.Sprc.Anast.). The vena cava in this embryo 

 is still in a transitory state of development and at present is represented by a 

 cava of Type ABC. Princeton Embryological Collection, no. 15. 



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