372 



Plate IV. 



i-'if!. 1 ;i. Dinwrphozoon iiohilc (Hincks). The four 

 lowermost zcHucia have low cup-shaped 

 oaH'ia. X 23. 



— 1 b. Zod'cia of the same species, lateral view. 



As the lateral walls in the ligure are not 

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



— 1 e. A transverse section tliroUf,'li a colony show- 



ing its two layers with e.\trcmcly dllTcrent 

 forms of zoiecia. In two zoieeia the vertical 

 part of the distal wall is seen with a multi- 

 porous ro.selteplate. Three small vaulted 

 rosette-plates are seen between the two 

 layers. X 40. 



— Id. The basal surface of some calcilied zocecia 



after the removal of the membranous zoce- 

 cia. The rosette-plate of the lateral wall is 

 seen and on one of the zocjecia two uni- 

 porous rosette-plates. X 40. 



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



same species. X 75. 



— If. Zocecia of the Alcyonidium-layer of the same 



species. X 23. 



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



ooecium of Dendroheaniu Murrdiiana i.Iohnst.); 

 endo- the endood-cium: 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 iL.). The uppermost zooe- 



cium shows a rudiment of an ocecium, and 

 the lowermost the mark left by a detached 

 OfEcium (ov.). Proximally to this the forked 

 distal wall is seen. X 40. 



— 4a— e. A zonccium with ooecium of C.oriiiicopina 



infunclihulala 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 saine o(Ecium- 



bearing zocrcium; it shows that the ooecium 

 is surrounded by a kenozo(ecium. X 23. 



— 5 a. Two zo<ccia of Cornncojiina grandis 'Busk), 



showing a finely dcntated cry|)tocyst. X 40. 



l'"ig. 5 b. The same zonecia, from the basal siii-facc. 

 X 40. 



— 5 c. A zooecium of the same s])ecies with a large 



avicularium. X 40. 



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



— 5 e. The avicularian mandible. X 55. 



— 6 a. Hiaritopora raJicifera Hincksi. X 23. 



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



X 23. 



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



X 55. 



— 7 a. Didymia simplex. Busk. The central zo(e- 



cium with an oa'ciura enclosed by a keno- 

 zo(Ccium. X 40. 



— 7 b. A zofEcium of the same species with o<i'- 



cium, from the frontal surface. X 40. 



— 7 c. A zod'cium of the same species with o(i'- 



eium, from the basal surface. The arched 

 distal wall is seen between the zocveium 

 and the kenozo(Ecium. X 40. 



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



same species with oircium. X 40. 



— 8 a. Dimelopia corniita Busk. X 40. 



— 8 b. A zo(Ccium of the same species with ooe- 



cium, from the basal surface. The pore- 

 chambers and the oval uncalcified part of 

 the ectooa-cium are seen. X 40. 



— 8 c. A zoa'cium of the same species from the 



basal surface. The pore-chambers and their 

 rosette-jjlatcs are seen. X 55. 



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



from above. X 55. 



— 8 e. A sagittal section through an oa-cium 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 cctoocecium as it gives the incorrect 

 idea that a covering membrane is found 

 here. X 75. 



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



from the frontal surface. X 40. 



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



X 40. 



