372 



Plate IV. 



Fig. 1 a. Dimorphozoon nobile (Hincks). The four 

 lowermost zocecia have low cup-shaped 

 ooecia. X 23. 



— lb. Zocecia of the same species, lateral view. 



As the lateral walls in the figure are not 

 split, only rosette-plates are seen. X 23. 



— 1 c. A transverse section through a colony show- 



ing its two layers with extremely different 

 forms of zocecia. In two zocecia the vertical 

 part of the distal wall is seen with a multi- 

 porous rosette-plate. Three small vaulted 

 rosette-plates are seen between the two 

 layers. X 40. 



— Id. The basal surface of some calcified zocecia 



after the removal of the membranous zoce- 

 cia. The rosette-plate of the lateral wall is 

 seen and on one of the zocecia two uni- 

 porous rosette-plates. X'40. 



— 1 e. The distal end of an avicularium of the 



same species. X 75. 



— If. Zocecia of the Alcyonidium-laj'er of the same 



species. X 23. 



— 2 a — 2 e. A series of developmental stages of the 



ocecium of Dendrobeania Murrayana (Johnst.) ; 

 endo- the endoooecium; ecto- the ectooce- 

 cium. The first four figures show the ascend- 

 ing part of the distal wall, the two lateral 

 halves of which meet at an angle. The first 

 three also show that the spines arise as 

 folds in the lateral margins of the zooecium. 

 X 40. 



— 3 a. Bicellaria ciliata (L.). The uppermost zoce- 



cium shows a rudiment of an ocecium, and 

 the lowermost the mark left by a detached 

 ocecium (ov.). Proximally to this the forked 

 distal wall is seen. X 40. 



— 4 a — c. A zooecium with ocecium of Cornucopina 



infnndibulata (Busk) in three different posi- 

 tions. The distal wall is seen in 4 b and 

 4 c. X 23. 



— 4d. A sagittal section through the same ooecium- 



bearing zooecium ; it shows that the ocecium 

 is surrounded by a kenozooecium. X 23. 



— 5 a. Two zocecia of Cornucopina grandis (Busk), 



showing a finely dentated cryptocyst. X 40. 



Fig. 5 b. The same zocecia, from the basal surface. 

 X 40. 



— 5 c. A zooecium of the same species with a large 



avicularium. X 40. 



— 5 d. The frontal surface of the avicularium. X 40. 



— 5 e. The avicularian mandible. X 55. 



— 6 a. Hiantopora radicifera (Hincks). X 23. 



— 6 b. The same species, from the basal surface. 



X 23. 



— 6 c. An avicularian mandible of the same species. 



X 55. 



— 7 a. Didymia simplex, Busk. The central zooe- 



cium with an ocecium enclosed by a keno- 

 zooecium. X 40. 



— 7 b. A zooecium of the same species with oce- 



cium, from the frontal surface. X 40. 



— 7 c. A zooecium of the same species with oce- 



cium, from the basal surface. The arched 

 distal wall is seen between the zooecium 

 and the kenozooecium. X 40. 



— 7 d. A sagittal section through a zooecium of the 



same species with ocecium. X 40. 



— 8 a. Dimetopia cornuta Busk. X 40. 



— 8 b. A zooecium of the same species with oce- 



cium, from the basal surface. The pore- 

 chambers and the oval uncalcified part of 

 the ectoooecium are seen. X 40. 



— 8 c. A zooecium of the same species fi'om the 



basal surface. The pore-chambers and their 

 rosette-plates are seen. X 55. 



— 8d. The distal wall of the same species, viewed 



from above. X 55. 

 • — 8 e. A sagittal section through an ocecium of 

 the same species. The outermost line 

 seen at a part of the basal surface of the 

 figure ought not to have been seen outside 

 the ectoooecium as it gives the incorrect 

 idea that a covering membrane is found 

 here. X 75. 



— 9 a. Brettia simplex (Mac Gilliv.). A zooecium 

 from the frontal surface. X 40. 



— 9 b. A zooecium of the same species, lateral view. 

 X 40. 



