416 



Plate XXIII. 



Fig. 1 a. A part of the kenozocecial layer of Retepora 

 tessellata Hincks. Three of the kenozooecia 

 are furnished with avicularia, from which 

 porechannels pass out to the surface of the 

 kenozooecia. Four of these pore-channels are 

 seen to perforate the lateral walls of the 

 adjacent kenozooecia. The opercular area of 

 the avicularia is furnished with a well-de- 

 veloped cryptocyst. X 56. 



— 2 a. Two kenozooecia from Retepora lata Busk, 



seen from the inner concave surface. The 

 inner, in size strongly reduced, very irre- 

 gular cavities of the kenozooecia are con- 

 nected through pore channels perforating 

 the lateral walls. X 40. 



— 2 b. A third kenozooecium of the same species, 



seen from the inner surface and in such a 

 position that the stratification of the basal 

 wall can be seen. The inner cavity, which 

 is much larger than that in the two other 

 kenozooecia, is placed near to the inner 

 surface and there is seen a number of pore- 

 channels and rosette-plates corresponding 

 to the cavities in the adjoining kenozooecia. 

 X 40. 



— 2 c. The same kenozooecium seen fi'om . the left 



side-walL Seven single-pored rosette-ijlates 

 are seen, the five hindermost of which cor- 

 respond with the pore-channels seen in the 

 left side of the figure 2 b. X 40. 



— 3 a. A longitudinal section through a branch of 



Retepora cellulosa Smitt. On the right side 

 are seen the zooecia, while the rest of the 

 branch is formed by the kenozocecial layers, 

 the youngest of which have covered a Spi- 

 rorbis. X 12. 



— 4 a. Rhgnchopora angulata n. sp. X 55. 



— 4 b. A zooecium of the same species, seen from 



the left side-wall. On the left side is seen 

 an avicularium. X 55. 



— 4 c. Zooecia of the same species, seen from the 



basal side after removal of the basal wall. 

 X 55. 



Fig. 4 d. Zooecia of the same species with ooecia. 

 X 55. 



— 4 e. The same species. The aperture with tlie 



operculum in situ. The beaded vestibular 

 arch is seen shining through the operculum. 

 X 100. 



— it The same species. Ocecium, seen a little 



from the pro.ximal part to make the screen- 

 like frontal lobe more distinct. This lobe 

 cannot be seen in fig. 4 d. X 55. 



— 4 g. Operculum of the same species. X 100. 



— 4h. Avicularian mandible of the same species. 



XIOO. 



— 5 a. Operculum of Rhynchopora scintillans 



(Hincks). X 140. 



— 6 a. Two zooecia of Microporella flabelligera n. 



sp. X 40. 



— 6 b. The same species. A zooecium with ocecium. 



X 40. 



— 6 c. Operculum of the same species. X 75. 



— 7 a. Conescharellina angulopora (Ten-Woods). 



Between the two avicularia is seen one of 

 the peculiar crescentic apertures, belonging 

 to certain kenozocecia. X 75. 



— 7 b. The same species. A crescentic aperture 



and two avicularia. X 75. 



— 7 c. Operculum of the same species. X 100. 



— 7 d. A transverse section of the same operculum. 



X 200. 



— 7 e. The aperture of the same species. X 75. 



— 7 f An avicularian mandible of the same spe- 



cies. X 200. 



— 8 a. Conescliarellina cancellata (Busk). Ooecium. 

 ^ X 55. 



— 8 b. An ooecium of the same speoies, from the 



side. X 55. 



— 9 a. Adeonellopsis foliacea Mac Gill. Four zooe- 



cia and a gonozooecium, X 40. 



— 10 a. A part of the frontal surface of Anarthro- 



pora monodon (Busk). X 200. 



— 11 a. A part of the frontal surface of Inversiula 



inversa (Waters). X 200. 



