PLATE IL 



Structure of the coenoecium. 



Figs. II — 13. — Ceplialodiscus levinseni. 

 Figs. 14 — 16. — C. gmciüs. 

 Figs. 17, 18. — C. sibogae. 

 Figs. 20, 21. — C. dodecalopJius. 

 Fig. 19. — Rliabdopleitra normani. 



Fig. II. C levinseni. — Part of the coenoecium (Greenough's biiiocular, a"). The diameter ^4 i? ^ 12 mm.; 



the length of the peristome i? ^^4,2 mm.: — z., zooids, each contained in a distinct compartment 



("zooecium") of the coenoecium; the varying positions of the pigment-Iine 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 (GreENOUGH, a'). For explanation of a, b, see text (p. 9); e, a secondary lamella. 

 Fig. 13. C. levinseni. — Two young peristomes (GreenüUGH, a^). 



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

 Fig. 15. C. graeilis. — Portion of a colony, shewing the continuous cavity of the coenoecium (Greenuugh 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; 



B, the filament shewn in fig. 14. 

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



a.,h. orifices. (For explanation of r — f, see text, pp. 12, 13). 

 Fig- 17- — C. sibogae. — End of a branch of the coenoecium (GREENOUGH, a^): — e.,f.,i., orifices. (For 



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

 Fig. iS. C. sibogae. An erect branch of tiie coenoecium, less highly magnified (Greenough, a"). The position 



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



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

 Fig. 19. Rhabdoplenra nonnani. — F'ree end of a peristome (Zeiss, C). (For explanation of lettering, see 



text, p. 8). 

 Fig. 20. C. dodecalophus. — Portion of coenoecium (GREENOUGH, a^). 

 Fig. 21. C. dodeealophus. — Portion of coenoecium, less highly magnified (GREENOUGH, a") : — b,e, orifices. 



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



yriie figures on /his B'late luere drawn as follozos: 



Greenough's binocnlar, a": — Figs. 11, 15, 18, 21. 



Greenough's binocnlar, a-: — Figs. 16, 17. 



Greenough's binocnlar, iv'-. — Figs. 12, 13, 14, 20. 



Zeiss, C: — Fig. 19. 

 All the figures ivere aftertuards rednced ^\^, or tzuo diameters]. 



