126 PEOCEEDIK-GS OF THE NATIONAL. MUSEUM vol.72 



a small calcareous finely perforated membrane. In erecting them- 

 selves their mandible forces the water toward the aperture. Their 

 presence is rather constant; however, certain rare groups of zooecia 

 are deprived of them and the tremocyst appears as in the marginal 

 zooecia. 



Other rare groups of zooecia are covered by a sort of smooth 

 pleurocyst on which one or two avicularia subsist. This is not proof 

 of old age, as Smitt wrote, for the group that we figure was placed, 

 on a young frond above the ordinary axial zooecia. 



The aperture was figured by Smitt as semielliptical. On our 

 photographs it appears for the most part as suborbicular and a little- 

 transverse. It is, moreover, rarely apparent and always buried at 

 the bottom of the tremocystal peristomie. The operculum is very 

 fragile, very thin, and of the same form as the aperture. 



On the interior the zooecia are rather regular, smooth (olocyst) ,, 

 with rather thick walls. The spiramen appears in the portion cor- 



responding to the external peristomie. The 

 place and the true form of the aperture is. 

 more evident on the lateral zooecia. 



Affinities. — ScMzoporella crihrifera Hincks,, 



FIG. 24.-CIGCL1SULA sEREu- 1^85, aud SchizovorelU fislieH Jullien, 1882, 



LATA smixt, 1877. A, B. opee- are ornamented with an analogous sievehko 



'''^"' ^ ^^ ovicell. They belong probably to the same 



family. Their aperture bears a proximal sinus which is lacking in 



Cigdisula serrulata. 



This species differs very much from the genotype in the absence 

 of the peristomial avicularia and in the form and nature of the 

 operculum. It can in reality be considered as the type of a new genus- 

 of the same family, but as we know no closely allied species and as 

 our information on the structure is still incomplete, we prefer to 

 wait for a more complete study. This is the last representative of 

 a family which was very important in the Gulf of Mexico of geologic 

 time. 



Occurrence. — Fowey Light, 15 miles south of Miami, Fia., 40 fms. 

 Albatross Station D. 2639, Straits of Florida; 25° 04^ 



50" N.; 80° 15' 10" W.; 56 fms.; coral sand. 

 Florida, 56-68 meters (Smitt). 

 Plesioty pes. —C&t. No. 7476, U.S.N.M. 



Family ADEONIDAE Jullien, 1903 



Genus ADEONA (Lamouroux, 1816) Levinsen, 1909 



ADEONA PLAGIOPORA Smitt, 1873 



Plate 23, Figures 4, 5 



1873. Porina plagiopora Smitt, Floridian Brj^ozoa. Kongl. Svenska Veten- 

 skeps-Akademiens Handlingar, vol. 11, p. 30, pi. 6, figs. 134, 135. 



