124 



KOTIFERA 



[CH. 



one is situated in the mid-dorsal 



18 AQ 



16 



FIG. 53. Hydatina senta, ventral view. 

 After Plate. Magnified. 



1. Lateral antenna. 2. Bladder. 

 3. Cingulum. 4. Eggs. 5. Vitel- 

 larium or yolk-gland. 6. Foot- 

 gland. 7. Gizzard. 8. Gastric 

 gland. 9. Germarinm or ovary. 

 10. Lobes of "groove" bearing stiff 

 setae. 11. Intestine. 12. Excretory 

 tube. 13. Mouth. 14. Ciliated tag 

 of the excretory system. 15. Oeso- 

 phagus. 16. Kenal commissure 

 or transverse tube uniting kidneys 

 above mouth. 17. Stomach overlaid 

 by reproductive organs. 18. Tro- 

 chus. 19. Uterus. 



lives. The larger eggs, which 



line, two are latero-ventral ; these 

 latter are in some genera fused 

 with one another. 



As in the Platyhelminthes, 

 so in Rotifers, the ovary, which 

 occupies a good deal of space in 

 the body-cavity, usually consists 

 of a vitellarium or yolk-gland 

 and agermariumor true ovary. 

 The latter lies between the former 

 and the stomach; it is incon- 

 spicuous and is more or less 

 hidden by the large cells of the 

 vitellarium. Both glands may 

 be paired. They are enclosed in 

 a membrane continuous with the 

 oviduct, which opens into the 

 cloaca behind the excretory duct. 



The above description relates 

 chiefly to the female Floscularia, 

 and in fact until 1874 the male 

 was unknown. It is much smaller 

 than the female (B, Fig. 50). As 

 a rule the male Rotifer, has a 

 single circlet of cilia, a brain, eyes, 

 excretory system and muscles all 

 more or less reduced, but there 

 is no mouth or alimentary canal. 

 The testis is large and the penis 

 is introduced into the cloaca of 

 the female, or in some cases is 

 thrust through the wall of the 

 body, and then the eggs are 

 probably fertilised in the ovary. 



Floscularia lays two kinds of 

 eggs during the summer, both of 

 which are thought to develop 

 parthenogenetically. Both kinds 

 accumulate between the foot and 

 the tube in which the mother 

 average five to eight in number, 



