Plate IV. 



Figures i 5 Halopsis ocellata A. Agassiz. 



Figure i. A male specimen, 35 mm wide, seen from the aboral side. - - Iceland. "Thor" stat. 179(04). 



x 2. 



2. Part of the bell-margin seen from the abaxial side; showing 5 tentacles, 4 cirri, i marginal 



vesicle, and the velum. From a specimen, 35 mm wide, from the Vestman Islands. x 28. 

 3. Mature male gonad. From the same specimen as fig. i. x 5. 



4. Mature female gonad. From a specimen, 30 mm wide, from between Iceland and the 



Faeroe Islands. - - x 5. 

 5. Bifurcated female gonad. - - Iceland, "Thor" stat. 174 (04). - - x 5. 



Figures 6 10 Tiaropsis multicirrata (M. Sars). 



6. Transverse section through radial canal with mature male gonads. Hrafnsfjord, Iceland. 



x 28. 



7. Transverse section through radial canal with immature female gonads. - - Veidileysafjord, 

 Iceland. - - x 28. 



8. Transverse section through radial canal with mature female gonads. Most of the eggs have 

 been detached, some eggs have not yet penetrated the ectodermal epithelium. - - Dyrefjord, 

 Iceland, August 4th 1896. - - x 30. 



9. Lateral view of the proximal part of a radial canal with female gonads, showing a number 

 of mature eggs situated on the outer side of the lateral wall of the canal. - - From the same 

 specimen. x 15. 



10. The same radial canal seen from the ventral edge. -- x 15. 



Figures 1 1 13 Phialidium islandicum nov. spec. 



ii. A specimen seen from the aboral side. -- Iceland, "Thor" stat. 176(04). - - x 2. 



12. Manubrium seen obliquely from the aboral side. - From another specimen from the same 

 locality. x 8. 



13. Section through the circular vessel and a marginal vesicle. - Iceland, "Thor" stat. 266 (04). 



- x 220. 



14. Phialidium hemispharicum (Gronovius). - - Section through the circular vessel and a mar- 



ginal vesicle. - - Myri Bugt, Iceland, July 24th 1904. - - x 220. 



