448 



Figs. 8 and 9 represent, respectively, a ventral and a dorsal 

 view of the same preparation. This case is another example of an 

 interesting variation within the Type. 



In the ventral view, Fig. 8, the V. cava posterior appears to 

 be formed by the union of two Vv. iliacae communes which, on 

 their part, are formed by the union of a V. iliaca externa and in- 

 terna. The above mentioned unions take place ventral to the 

 arteries. By means of a narrow venous isthmus, which lies ventral 

 to the Aorta, the so-called Vv. iliacae communes communicate with 

 each other. The conditions represented in Fig. 8 more closely cor- 

 respond to those figured by Hochstetter for Halmaturus etc., 

 than any other examples observed by the writer. Fig. 8, in all 

 probability, represents an instance in which the fusion of the Vv. 

 hypogastricae-sacrales has not taken place, or is incomplete. 



In the dorsal view of this preparation. Fig. 9, the conditions 

 are not unlike those represented in Fig. 7. Here a union takes 

 place, by means of a relatively small vessel (D.U.) that lies dorsal 

 to the A. iliaca communis sinistra, between the V. iliaca interna 

 sinistra and the V. iliaca externa sinistra. 



The relations of the V. sacralis media to this dorsally situated 

 vessel (D.U.), differ in the two preparations in question and can 

 best be understood by comparing Figs. 7 and 9. 



Sul)-Type III, B. Those cases in which the principal 

 union between the Vv. iliacae internae and ex- 

 ternae lies dorsal to the arteries in question 

 (Aa. iliacae communes etc.). 



Eight examples of this Sub -Type were met with distributed 

 among four males and four females. 



Figs. 10 and 11 represent ventral views of the same pre- 

 paration. In Fig. 11, howewer, the arteries have been removed so 

 as to show the union {D.U.) between Vv. iliacae internae and 

 externae that lies dorsal to the arteries. 



In Fig. 10 the V. cava posterior appears to be formed by the 

 unions of three veins, by the two Vv. iliacae externae and by a 

 relatively small vein (F.C/.) that lies ventral to the arteries. This 

 vein (F. Ü.) extends between the Vv. iliacae internae, where they 

 unite ventral to the A. sacralis media, and the point of union of 

 the two Vv. iliacae externae. 



In Fig. 11 the vessels {D.U.) which form the principal union 

 between the Vv. iliacae internae and externae are plainly seen, since 



