NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 147 
ing of the frontal walls; but it does not really belong to this genus because it has no 
lyrula nor oral avicularium and because the apertura is not semilunar. 
Occurrence. —Lower Miocene (Bowden horizon): Cercado de Mao, Santo 
Domingo (rare). 
Holotype. —Cat. No. 68647, U.S.N.M. 
SMITT1NA PORIFERA Hlncks, 1884. 
Plate 38, fig. 9. 
1884. Porella marsupium forma pori/era Hincks, Report on Polyzoa of Queen Charlotte Islands, 
Annals Magazine Natural History, ser. 5, vol. 13, p. 50 (sep. 24), pi. 4, fig. 4. 
1887. Porella marsupium, var. porifera Waters, Tertiary Cheilostomatous Bryozoa fromJNew Zea¬ 
land, Quarterly Journal Geological Society London, vol. 42, p. 63. 
Description. —The zoarium is incrusting. The zooecia are distinct, swollen, 
separated by a deep furrow, very convex, perforated by some pores widely spaced. 
The frontal is a pleurocyst garnished laterally with six large areolar pores, of which 
the two superior ones are sometimes changed into avicularia. The apertura is deep, 
hidden by the peristomie and by a small, salient, orbicular, oral avicularium. The 
peristome is thin and bears four small spines which are often replaced by a small 
distal orbicular avicularium (rarely two). There is a very small lyrula hidden by 
the frontal avicularium. The ovicell is globular, salient, smooth; it opens above 
the operculum by a very large opening. 
Measurements. —Apertura- 
ha = 0.12 mm. 
Za = 0.12 mm. 
Zooecia- 
Lz = 0.45 mm. 
I lz = 0.28 mm. 
The avicularium chamber forms a frontal gibbosity perforated by four large 
pores. The latter characterize the species, for they do not exist in Porella mar¬ 
supium MacGillivray. 
Occurrence. —Pleistocene: Santa Monica (Long Wharf Canyon), California (rare). 
Geological distribution. —Pliocene of New Zealand (Waters). 
Habitat. —Queen Charlotte Islands (Hincks). 
Plesiotype. —Cat. No. 68648, U.S.N.M. 
Genus PORELLA Gray, 1848. 
(For description, see Bulletin 106, U. S. National Museum, p. 479.) 
PORELLA BELLA Busk, 1860. 
Plate 1, fig. 12. 
1860. Lepralia bella Busk, Zoophytology, Quarterly Journal Microposcopical Science, vol. 8, pi. 27, 
fig. 2, 3. 
1873. Escharella landsborovi Smitt, Floridan Bryozoa, pt. 2, Kongl. Seven. Vet. Akad. Hand., vol. 
11, no. 4, p. 60, pi. 10, figs. 201, 202. 
1880. Smittia bella Hincks, British Marine Polyzoa, p. 352, pi. 42, figs. 9, 10. 
1919. Porella bella Canu and Bassler, Geology and Paleontology of the West Indies, Bryozoa, 
Publications of the Carnegie Institution, no. 291, p. 93, pt. 1, fig. 15. 
We are not certain that Busk’s species is identical with that of Smitt, as the 
former author represents it, but is evident that the characters of our Antigua fossil, 
although it is poorly preserved, are in harmony with Smitt’s figures. Following 
are the measurements of this fossil. 
[k = 0.16 mm. n . (1-2 = 0.90 mm. 
Apertura) fo _ 0 2Q mm Zooedaj fo _ Q 7Q mm 
