34 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 7G 



zooecial. This is perhaps only an appearance, and it is necessary to 

 dissect this ovicell in order to be certain of its nature. 



We do not believe that the mandibles of this species are really the 

 bristles of vibracula. They do not have the organs of articulation 

 which permit movement in every direction. To us they are setiform 

 mandibles of true avicularia, for they can move only in a certain way, 

 variable, however, in each species. 



Biology. — Our specimens from the Galapagos Islands incrust dead 

 shells and Lithothamnion. They were in reproduction on April 7 to 9, 

 1888, and in March, 1902. They appear to have lived on the bottoms 

 dredged at that time. The species has not yet been rediscovered 

 living in the Gulf of Mexico. It has lived there, however, because 

 we have found it as a fossil in the Pleistocene of Panama. It was 

 doubtless transported from Madeira by the equatorial current. Its 

 presence in the Pacific is therefore ancient and dates to the time when 

 the Isthmus of Panama had not yet formed. The large migratory 

 fish have transported its larvae across the Pacific to the Hawaiian 

 Islands and Tahiti, and even farther. 



The length of the mandibles is equal to the distance between the 

 two avicularia. The mandibles form a cross on the frontal. They 

 appear to be tactile organs, but special to the zooecium which bears 

 them. 



Occurrence. — Galapagos Islands, D. 2813 and D. 2815; Hawaiian 

 Islands, 325-483 meters and 5.3° C, D. 3813 (265-302 meters); 

 Tahiti and New Zealand (Hincks) ; Madeira (30 fathoms). Red Sea 

 and Gulf of Suez (Norman). Pleistocene of Panama (Canu and 

 Bassler). 



Plesiotypes.—Qdit. Nos. 8505, 8506, U.S.N.M. 



Family ADEONIDAE Jullien, 1903 

 Genus ADEONA Lamouroux, 1916 



ADEONA TUBULIFERA, new species 



Plate 5, Figures 6-9 



Description. — The zoarium incrusts shells and nullipores. The 

 zooecia are distinct, separated by a furrow, elongated, elliptic, 

 swollen ; the frontal is convex and ornamented with two rows of large 

 areolar pores. The peristomie is tubulai\ very long, and very oblique 

 on the young zooecia, shorter and little oblique on the much calcified 

 zooecia; the peristome is thick and smooth; the peristomice is sub- 

 orbicular, more often somewhat transverse. A thin triangular avicu- 

 larium, the beak oriented superiorly, is placed on the peristomie. The 



