THE BRYOZOA BASSLER. 



367 



— OP. 



" p 



Op,^Ov 



zp 



7 9 



Fig. 9. — Ovicell structure in the Cheilostomata. Op=OparcuIum ; Ov=ovicell ; Zd=dis- 

 tal zooecium ; Zp=proximal zooecium ; Loc=locella ; Pr=peristomie or tube developed 

 by growth of peristome. The thin broken line indicates the membraneous ectocyst, 

 while the thin double line represents the operculum. 



1—2. Longitudinal sections through zooecia with an endozooecial ovicell. The ovicell is 

 within the zooecium itself and the operculum closes both the zooecium and the ovi- 

 cell. In 2 a fold of the zooecial wall separates the ovicell from the zooecium. 



3. Micropora coriacea Esper. A group of zooecia, X25, with two showing the endo- 

 zooecial ovicell and the operculum closing the ovicell as well as the zooecia. 



4. Yclumella levinseni Canu and Bassler. Zooecia, X40, with the two uppermost bear- 

 ing the small endozooecial ovicell. 



5-7. Sections showing three types of hypcrstomial ovicell in which the ovicell is placed 

 on the distal zooecium. In 5 the ovicell opens below the operculum, and there is thus 

 only one aperture. In 6 there are two apertures, and the operculum in opening closes 

 the ovicell. In 7 the ovicell opens above the operculum. 



8. Three ovicelled zooecia of Ramphonotus minax Busk, X50, illustrating the hyper- 

 stomial form of ovicell. 



9. Sketch of endotoichal ovicell in which the ovicell is completely separated from the 

 zooecium and its orifice is removed from the aperture and placed in the same plane. 



10. Two zooecia, X50, of C'ellaria sinuosa Hassall, showing the apertures of the small 

 endozooecial ovicell in advance but on the same plane as the large zooecial apertures. 



11. Ovicelled zooecia, X36, of Umboiwla verrucosa, Esper with hyperstomial ovicell 

 opening largely above the aperture. 



12—13. Hyperstomial ovicells. In 12 the ovicell is placed in a deep cavity of a distal 

 zooecium. The operculum is very oblique and operates in a special chamber or lo- 

 cella. 13 represents a special type in which the ovicell opens above the operculum 

 in the peristomie or tube formed by the growth of the peristome. 



14. A group of zooecia, X23, of Tubiporella magnirostris MacGillivray, with two peri- 

 stomial ovicells. 



15. Diagram of a peristomial ovicell showing its formation by an enlargement of the 

 peristomie. 



16. Typical example (Phylactella lalrosa Busk) of the recumbent ovicell, X30, in which 

 the ovicell is placed on the distal wall of the zooecium itself. 



17. A sketch of a recumbent ovicell showing its relations to the zooecia and operculum. 



