PLATE XXIV. 

 [Proc. Wash. Acad. Sci., Vol. II, PI. XX.] 



FlG. 5. Bugula purpurotincta Norman, frontal view. The two lower zoecia on 

 the left show the small size of the oecia (a?.) compared with that of the 

 embryo (emb.) (at;.) avicularium. 



5. An avicularium which had broken away from its zoecium ; peduncle 

 (ped.), mandible (man.), beak (), muscular apparatus (mus. app.). 



6. Dorsal view of the same, showing spine (sp.) and avicularium (at/.) as 

 seen from the back, and the mode of bifurcation (bifur.). 



7. Flustra lichenoides sp. nov. Frontal view, showing oecia (of.) and vari- 

 ation in the number of flattened spines (yf. sp.). 



7. A single frond of the same, natural size. 



8. Dorsal surface of the same, showing the radical fibers (r. /.) and their 

 mode of attachment to the zoecia. 



9. Membranipora sandalia sp. nov. Upper surface, representing a few 

 zoecia in the second stage. The aperture (ap.) occupies the distal end 

 of the zoecium. Below it is the uncalcified area (ar.) upon which an 

 avicularium will be formed, and toward which the calcareous thickenings 

 converge. 



90. One zoecium of the same near the edge of the colony. It is oblong in 

 shape and the aperture (/) occupies the whole of the front. 



gb. A zoecium of the same, showing the beginnings of calcification (/.) 

 and (a*.). The future aperture (a/.) is already laid off. 



[338] 



