ECONOMY OF THE ACEPHALOCYSTS OF AUTHORS. 57 1 



Fig. 10. Portion of membranes of the vesicle of Csenurus, highly magnified, shewing several ovules in 

 different stages of discoidal development ; A A A ovules in the first, second, and third stages of 

 discoidal development, shewing vessels running to them from all directions, for the purpose of supply- 

 ing them with nourishment ; B B another ovule much more advanced, shewing how the external 

 membrane is pushed out by the increasing ovule, and forms a kind of base. 



Fig. 11. Young pedicle and head of Cscnurus cerebralis, after it has properly assumed the verticle period 

 of growth. A The young pedicle ; B the base, shewing how the external membrane is pushed to- 

 gether and folded upon itself. 



Fig. 12. Greatly magnified view of the head of Csenurus cerebralis seen from above. A double circlet 

 of teeth ; B acetabula, or suckers, which are situated round the head. In this instance there were 

 five of these, the general number being four. 



Fig. 13. Pedicle and head of Camurus. A head; BB cut edges of the external walls of head; 

 C diaphragm of cellular tissue separating head from pedicle ; D D cellular tissue forming walls of 

 pedicle ; E thin layer of external membrane of vesicle, which covers the head and pedicle ; F inter- 

 nal lining membrane ; G H ovaries, or ovule cells. 



