402 Venous System of Didelphys Marsupialis 
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EXPLANATION OF PLATES. 
All of the Figures on Plates I to V are life sized drawings of the caudal 
end of the posteava of Didelphys marsupialis and illustrate the variable 
manner in which the posteava is formed in this animal. With the exception 
of Fig. 23 only that portion of the postcava is represented which lies 
caudal to the Vv. spermaticae internae. In Fig. 23 the entire “ postrenal 
division ” of the posteava is represented. The names of all the vessels are 
indicated on three Figures (Fig. 1, Type I; Fig. 8, Type II, and Fig. 23, 
Type III, C, which can be used in identifying the vessels in the other Figs. 
Fig. 3 is only partially lettered). 
The following abbreviations app.y to the lettering on Figs. 1, 3, 8 and 23: 
(d and s refer to dextra and sinistra, respectively). 
A. i. e., A. iliaca communis. 
A. i. e., A. iliaca externa. 
A. i. i., A. iliaeca interna. 
Ao., Aorta. 
A. s. i. a., A. spermatica interna anterior. 
