24 PROCEEDINGS OF THE NATIONAL, MUSEUM vol. 76 



Measwrements. — 



I Aa= 0.12-0. 14 mm. . (Zs = 0.60-0.80 mm. 



Apertura|^^=Q;L6mm. /ooecmmj Zs =0.40 mm. 



Structv/re. — The zooecia are surrounded by large dietellae, but these 

 are not special to each cell as 'in Adeona. They are common to the 

 adjacent zooecia. The larger correspond to the avicularia which do not 

 belong therefore in reality to the zooecium on which they appear placed 

 but are truly interzooecial. The decoration on the young zooecia is 

 very elegant. Here 8 to 12 tremopores are tubular and salient. The 

 interstices fill up the progress of calcification and the frontal then 

 has only radial costules and large lateral pores. Under this aspect 

 they measure 0.60 by 0.40 mm. and the aperture 0.10 by 0.12 mm. 



The colonies are large, of irregular form, vaguely ramified and 

 with a curious aspect. The section shows the habitual arrangement 

 of the superposed lamellae. The base is very broad. The summit of 

 the branches, on the contrary, is very small, for the lamellae are here 

 less numerous. The result of this singular arrangement is the orien- 

 tation of the zooecia toward the base, an arrangement absolutely con- 

 trary to that observed on the other cheilostomes. As all the colonies 

 were separated from their substratum without showing a trace of rup- 

 ture we would judge that the latter was very fragile. They were 

 undoubtedly attached beneath the marine algae. 



This particular arrangement of superposed lamellae is frequent 

 in the Ceriopores and the Heteropores in which the colonies are 

 ascendant and more or less ramose. But their tubes are not oriented 

 and we can very well conceive the normal arrangement of their 

 tentacles. Enantiosula manica is, on the contrary, a cheilostome with 

 oriented cells, and we can not see any other cause for their apparent 

 inversion than the reversal of the colony itself. 



The operculum is of great simplicity; its bell form is similar to 

 that of Godonella and we have not seen any muscular attachment. 

 The mandibles are more often unguiculate, rarely straight. 



Biology. — The habits of this species are very curious. Each 

 colony lives with its head at the base, attached to the more or less 

 mobile substratum, as the irregularity of the forms observed proves. 

 The food thus captured must also be rather special and very alnm- 

 dant in order to assure the growth of a relative large edifice and of 

 the unusual cells. 



Neither the beak of the avicularia nor the mandible are in im- 

 mediate contact. The simultaneity of the movements of many cells 

 at a time is certainly probable, since the avicularia are interzooecial 

 and in contact with their mesenchymatous fibers which pass through 

 the entire colony. The mandibles appear to close when the tentacles 

 are withdrawn into the tentacular sheath. 



