4on 



Plate XV. 



KiR. 1 a 



— 11) 



— 1 f 



— Id 



Vrceolipora nana Mac Gilliv. , witli open 

 operculum. The li^uie only shows the strong- 

 est of the longitudinal ridges, which keep 

 the covering membrane stretched. Three 

 Od'cia are seen. X 40. 



Two zo(ecia of the same species with ocrcia, 

 from the frontal surface. X 40. 

 \ sagittal section through three zoa'cia of 

 the same species with o(ecia. The covering 

 membrane, the lowermost part of which 

 represents the ectood-ciuni, is too thick, as it 

 has been drawn with a double outline to 

 make it distinct, (look V\. XXIV., Ilg. 11.). 

 X 40. 



A zoiecium of the same species with oeecia, 

 from the basal surface. The uniporous ro- 

 sette-plates of the basal surface and of the 

 distal wall are seen. X 40. 

 1 e. A trausvcr.se section through a branch. Two 

 zoa'cia and three of the ridges, which kee]) 

 the covering membrane stretched, are seen. 

 X 40. 



1 f. .\ transverse section through the pro.vimal 



part of an oiecium and through a portion 

 of the adjacent zoa'cium. The endoo(ecium 

 is seen innermost and on each side of its 

 aperture one of the trapeziform i)rojections 

 which contribute to keep the covering mem- 

 brane stretched. On each side of the cover- 

 ing membrane intcrnallj' is seen the collar- 

 shaped ridge which surrounds the proximal 

 part of the occcium, and lowest <lown the 

 separating wall towards the adjacent zooe- 

 cium. Outside the eudoo(ccium the distal wall 

 with its roscttc-plates is seen. (On account 

 of incorrect shading it seems to be arched). 

 X S."). 



2 a. Eulhyris obtecia (Hincks). On tlic marginal 



zoa'cia the peculiar processes are seen, by 

 which the covering membrane is kept out- 

 stretched. X 40. 



2 b. Four zo(ecia of the same species, from the 

 basal surface. Besides the rosette-plates a 

 number of filiform, calcified elongations are 

 seen. X 40. 



2 c. .\ sagittal section through two marginal zo(C- 

 cia. The internal lateral processes arc visible 

 and also the connections between the cryp- 

 tocyst and the covering membrane. X 40. 



2d. Sagittal section through ordinary zocccia. 

 X 40. 



2 e. The processes of the lateral wall, from the 

 uter surface. X 40. 



l-ig. 2 



— ;i: 



— 31 



— 3 ( 



.■jb. 



— (i a 



Oh, 



fi c 

 7 a, 



Operculum of the same species. X 10(1. 

 MUroiiorclla niari/inalu (Kraussi. X 40. 

 The distal end of a zoan'ium of the same 

 species. X 100. 



Four zorecia of the same s|)ecies, from the 

 basal surface. In addition to the marginal 

 pore-chambers each basal, zixccial surface 

 shows a rosette-plate and an opening for 

 communication with zodcia in the opposite 

 layer. X 40. 



The operculum of the same species. X 140. 

 Hadical fibres of the same species. X 40. 

 A vibracular llagellum of the same species. 

 X 7.-.. 



Microporella flabellaris (Husk). X 40. 

 The distal end of a zixecinm of the same 

 species. X 40. 



The same s])ccies from the basal surface. 

 Besides the basal wall of the porc-cliambers 

 the small triangular basal surface of the 

 vibracular chamber is .seen lowest down to 

 the right on the four zon?cia. On some zoce- 

 cia the basal surface shows a rosette-plate, 

 and on others an opening corresponding with 

 a roscttc-platc in an opposite zoiecinm. 

 X 40. 



Hadical lihres of tlic same s])ecies. X 40. 

 The operculum of the same species. X 140. 

 The aviculai'ian maudihlc of the same spe- 

 cies. X 5,5. 



The fii'st three zoiecia of a colony of Micrn- 

 jiorella ciliala (Palla.s). The original aperture 

 of the primary zoiccium, which is surround- 

 ed by spines, is almost closed to a pore. 

 X .'iS. 



The aperture of Microporella ciliala. A well- 

 dcvcloped vestibular arch is seen and the 

 supporting beam is furnished with a pair of 

 lateral teeth. X 200, 



Microi>orell<i ilecorala (Heuss). The zod'cium 

 is furnished with three distal pore-chambers, 

 and the curved belts on the (xecium, at the 

 base iif which arc seen the line pores of the 

 cudoocccinm, arc canal-like cavities between 

 the cndooiecium and the distal calcified part 

 iif the ectooiecimn. Between these canals, 

 which open through a circle of ])ores, the 

 two layers of the ocecium have united. X 40. 

 A portion of the occcium more highly mag- 

 nified. X 75. 



An opercnlum of the same species. X 100. 

 The aperture of Mirropiirrlla Maliisii (And.). 

 X 100. 



