60 PROCEEDINGS OF THE NATIONAL MUSEUM vol.72 



ovicell is small and endozooecial. Sometimes small tubercles appear 

 sporadically between the zooecia. 



■nr s r\ ' [^^0 = 0.12 mm. 



Measurements. — Opesmmi, ^ ^_ 



^ Uo = 0.07mm. 



„ . Lz = 0.25 mm. 

 Zooeciai -, . _ . 



uz = 0.20 mm. 



Biology. — All of our specimens were dead. The number of species 

 of bryozoa which encrust gastropods is rather restricted, and they are 

 generally small. They appear to find in the irregularities of the sur- 

 face of moUusks conditions unfavorable to their development. 



Occurrence. — Albatross Station D. 2639, Straits of Florida; 25° 04' 

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



Hohtype.—C&t. No. 7498, U.S.N.M. 



Genus FLORIDINA Jullien, 1881 



The retractor muscles of the polypide are attached in the median 

 axis of the zooecium. The opesiular indentations are symmetrical, 

 very large, limited above by the two very salient opesiai processes 

 and placed on each side of a much produced, semitubular, polypidian 

 convexity. The zooecium is closed by an operculum attached to the 

 ectocyst; the opercular axis of rotation is located above the two 

 opesiai processes. The onychocellaria are straight, without the 

 small distal canal, rounded at their apex; the mandible is bimem- 

 branous. Ovicell endozooecial. 



The genus Floridina is apparently restricted to the equatorial zone 

 in the Gulf of Mexico for it has not yet been found in any other lo- 

 cahty. We have observed it fossil in the Jacksonian of Mississippi, 

 Georgia, and North Carolina. It disappeared in the Vicksburgian 

 of Alabama and Mississippi, probably due to cooling of the tem- 

 perature. 



FLORIDINA ANTIQUA Smitt, 1873 



Plate 6, Figure 1; text Figures 8c, d 



1873. Mollia antiqua Smitt, Floridan Bryozoa, pt. 2. Kongl. Svenska 

 Vetenskaps-Akaderniens Handlingar, vol. 11, no. 4, p. 12, pi. 2, 

 fig. 73 (not Busk 1853). 



1881. Floridina antiqua Jullien, Nouvelle division des Bryozoaires cheilo- 

 stoiniens. Bulletin de la Soci6t6 Zoologique de France, vol. 6, p. 14. 



Structure. — The microporoid structure of this species did not escape 

 Smitt who allied it with the group Micropora, Thalamoporella, and 

 Steganoporella with a certainty really remarkable at an epoch when 

 the anatomical studies were still much restricted. Jullien in 1881 

 and 1888 was the first to discover the function of the opesiular 

 muscles and to determine the structure of the frontal. Our generic 

 definition of 1920 is correct, as our new study of the genotype 

 confirms it. 



