NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 131 



HIPPOPORINA LATA(7) Smltt, 1872. 



Plate 1, fig. 11. 



1872. Gemellipora lata Smitt, Floridan Bryozoa, pt. 2, Kongl. Svenska Vetenskapa-Akademiens 

 Handlingar, vol. 11, No. 4, p. 36, pi. 7, fig. 157. 



1919. Hippoporina lata Canu and Bassler, Geology and Paleontology of the West Indies, Bryozoa, 



Publications of the Carnegie Institution at Washington, No. 291, p. 93, pi. 1, fig. 14. 



This recent species was described from specimens from the Floridan waters and 

 the species itself is confined to this region. A very mediocre fossil specimen of 

 doubtful determination has been found in the strata of Antigua. 



Occurrence. — Oligocene (Antigua formation) : Rifle Butts, Antigua, Leeward 

 Islands (rare). 



Plesiotype.—C&t. No. 68607, U.S.N.M. 



Genus fflPPODIPLOSIA Canu, 1916. 



(For description see Bulletin 106, U. S. National Museum, p. 393.) 



HIPPODIPLOSIA BACCATA Canu and Bassler, 1920. 



Plate 3, fig. 1. 



1920. Hippodiplosia baccata Canu and Bassler, Monograph of the Early Tertiary Bryozoa of North 



America, Bulletin 106, U. S. National Museum, p. 397, pi. 87, figs. 5, 6. 



This species, which was based on specimens from the Vicksburgian of Missis- 

 sippi, is represented in Lower Miocene strata at Bowden, Jamaica. In these Mio- 

 cene specimens the tremocyst is separable and the intensity of the calcification is 

 very active in the ancestrular region. 



Occurrence. — Miocene (Bowden marl): Bowden, Jamaica (rare). 



Geologic distribution. — Vicksburgian of Mississippi. 



Plesiotype.— Cat. No. 68608, U.S.N.M. 



HIPPODIPLOSIA BIGIBERRA. new species. 



Plate 12, fig. 10. 



Descriftion.^The zoarium incrusts shells. The zooecia are distinct, separated 



by a furrow, elongated, subrectangular; the frontal is somewhat convex, perforated 



by a dozen of small tremopores and ornamented with two gibhosites symmetrically 



placed in the vicinity of the apertura, which they hide and partially deform. The 



apertura is elliptical, elongated; two small, deep cardelles separate a large anter 



from a small poster. 



f^ia =0.17-0.19 mm. ^ . fZ2=0.50mm. 



Measurements.-AY>evtura>^ ^^ =0.15-0.17 mm. ^^°^'''^\ ^ =0.35-0.45 mm. 



Structure. — The aspect of the apertura is very deceiving in a photograph. It 

 appears to resemble that of Gemellipora, but this is an optical illusion arising from 

 the projection on the same plane of the different zooecial elevations. In reality 

 the apertura is eUiptical, but its proximal portion is deformed by two frontal gib- 

 hosites which appear thus separated by a false rimule. By inclining specimens the 

 true form of the apertura is visible. 



Occurrence. — Miocene (Yorktown formation) : 3 miles southwest of Petersburg, 

 Virginia (rare) . 



Holotype.—C&t. No. 68609, U.S.N.M. 



