PLATE XXIII. 



Fig. 1. A hydrocaulus of Halecium sp. {tenellum Hincks äff.), x 18. 



— 2. Two hydrothecae of the same species, x 50. 



— 3. A colony of Halecium sp. {minutiim Broch afif.). x 18. 



— 4. A piece of the same colony, x 80. 



— 5. Coppinia of Toichopoma obliquum. Natural size. 



— 6. A piece of the same Coppinia. x 11. 



— 7. A little part of the surface of the Coppinia with four hydro- 



thecae, two of which are cut off just at the bottom, x 60. 



— 8. One of the transformed hydrothecae from the Coppinia, with 



closed and with opened operculum, x 60. 



