PLATE XXII. 



Figs. 1 — 3. Smittina arctica Norman. 

 Fig. 1. Zooecia and ooecia. 



— 2. Distal part of a zooecium showing avicularium, me- 



dian tooth and operculum. 



— 3. Operculum with the chitinous ridges. 

 Figs. 4—9. Porella fragilis n. sp. 



— 4. Zooecia and ooecia, frontal surface. 



— 5. Avicularia. 



— 6. Zooecia in lateral view. 



— 7. Aperture. 



— 8. Basal wall of the zooecia. 



— 9. Operculum. 



Figs. 10 — 14. Lepraliella hippopiis Smitt. 

 Fig. 10. Zooecia. 



— 11. Upper part of a zooecium showing the aperture and 



two triangular hinge teeth. 



— 12. Zooecia with ovate avicularia. 



— 13. Zooecia and ooecia with suturai lines. 



— 14 a, b, с Opercuia. 



