Plate IV. 



Figures i — 5 Halopsis occllata 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 ■muliicirraia (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 11 — 13 Phialidimn islandiami nov. spec. 



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



— 12. Manubrium seen obliqneh' 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. Phialidiu>n heniisplKrricum (Gronovius). — Section through the circular vessel and a mar- 



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



