THE DEVELOPMENT OP THK TBMNOOEPHAl.E.E. 
44 i 
Fig. 17. — Portion of a section passing through the endocoele at a 
stage similar to that represented in fig. 9, showing the developing 
excretory sac, and its connection with the endocoele. 
Figs. 18 and 19. — -The excretory sac in the adult; fig. 19 shows a 
f)art of the system of capillaries in which are numerous dame-cells, 
given off from the vesicular vessel and ramifying through the wall of 
the sac. Reproduced from a ' Monograph of the Temnocephaleas.’ 
pi. X, dgs. 11 and 12. 
Fig. 20. — Portion of a section of an egg with far advanced endocoele 
and distinct brain and excretory sacs, showing what is supposed to be 
the first trace of an endodermal primordium. 
