PLATE 11. 



Structure of the coenoecium. 



Figs. II — 13. — Cephalodiscus levinseni. 

 Figs. 14 — 16. — C. gracilis. 

 Figs. 17, 18. — C. sibogae. 

 Figs. 20, 21. — C. dodecaloplius. 

 Fig. 19. ■ — Rhabdopleiira normani. 



Fi'T. II. C. levinseni. — Part of the coenoecium (GreENOUGH's binocular, a"). The diameter yi!/) = 12 mm.; 

 the length of tiie peristome Z>'^=4,2mm.: — ;;., zooids, each contained in a distinct compartment 

 ("zooecium") of the coenoecium; the varying positions of the pigment-line indicate a considerable 

 variety of position in the proboscis; o., orifice; pst., peristome; e., embryos. 



Fig. 12. C. levinseni. — The peristome marked A in fig. 11, to shew the laminated structure of the coe- 

 noecium (GreeNOUGII, a'j. For explanation of a, b, see text (p. 9); c, a secondary lamella. 



Fig. 13. C. levinseni. — Two young peristomes (GreenouGH, a''). 



Fig. 14. C. gracilis. — The peristomial filament marked B in fig. 15 (Greenough, a'). 



Fig. 15. C. gracilis. — Portion of a colony, shewing the continuous cavity of the coenoecium (Greenough a") 

 — z., masses of zooids, which are so crowded that their limits are not easily seen ; b., bud ; e., embryos 

 o., orifices; a., an occluded orifice; fil., peristomial filaments of coenoecium, surrounding orifices 

 /), the filament shewn in fig. 14. 



Fig. 16. C. gracilis. — ■ End of another branch, more highly magnified than fig. 15 (Greexough, a'-): — 

 a.,b. orifices. (For explanation of c^f, see text, pp. 12, 13). 



Pig. ly. — c. sibogae. — End of a branch of the coenoecium (GreenougH, a^): — c.,f.,i., orifices. (For 

 explanation of other letters, see text, pp. 14, 15). 



Fig. 18. C. sibogae. An erect branch of the coenoecium, less highly magnified (GREENOUGH, a"). The position 

 of the orifices is indicated by the peristomial filaments (y?/.). The dark patches are foreign inclusions: — 

 B., part of the encrusting base of the coenoecium. 



Fig. 19. Rhabdopleiira nonnani. — Free end of a peristome (Zeiss, C). (For explanation of lettering, see 

 text, p. 8j. 



Fig. 20. C. dodecaloplius. — Portion of coenoecium (Greenough, a''). 



Fig. 21. C. dodecaloplius. — Portion of coenoecium, less highly magnified (GrkenouGH, a"): — b,c, orifices. 

 (For explanation of other letters, see text, p. 16). 



[ The figures on this Plate zvere draxvn as follows : 



GreeNOUGH's binocular, a": — Figs. 11, 15, 18, 21. 



GreeNOUGH's binocular, a-: — Figs. 16, 17. 



GreENOUGH's binocular, a'': — Figs. 12, 13, 14, 20. 



Zeiss, C: — Fig. 19. 

 All the figures were afterwards reduced '/j. or two diameters]. 



