90 



Mr. H. A. Buylis on 



Fiar. 3. 



Fisr. i. 



V.Sem. 



— £.Ap. 



Heterorrh is erumenifer. 



pjo-. 3. — Sagittal section, slightly to the right of the middle line (partly 

 diagrammatic). B., " bladder " of excretory vessel ; C.S., cirrus- 

 sac ; C. V., collecting excretory vessel ; D., diverticulum of 

 excretory sac ; E.Ap., aperture of excretory sac ; E.S., cavity 

 of excretory sac (on the ventral side of the sac part of its 

 epithelium has become separated from the basement-membrane) ; 

 O.S., oral sucker ; U.S., receptaculum seminis ; S., shell-gland ; 

 Ut„ uterus ; Vag. } vagina ; V.S., ventral sucker ; V.Sem., 

 vesicula seminalis. 



Fig. 4. — Outline drawing of three eggs, highly magnified. In two of 

 them the operculum is partly separated from the rest of the 

 shell. 



