NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
313 
,, , . ,/ia— 0.15 mm. 
Measurements .- — Aperture { , „ .. „ 
1 to=0.15mm. 
Zooecia 
Lz= 0.65-0.72 mm. 
lz= 0.35 mm. 
Variations . — The structure of this species is quite remarkable. The lacunae are 
transformed into true areolae serving for the passage of the mesenchyme fibers, 
and of the endocyst, which is situated under the ectocyst; the endocyst continues 
its calcareous secretion over each areola and carves out a great number of polygonal 
pieces on each zooecium. 
The smooth collar which surrounds the cribriform area is formed of as many 
pieces as it has areolae and covers the shield of the primitive costules. 
The ooecial cover is composed of many calcareous pieces arising from as many 
pores of the distal zooecia and even the adjacent zooecia; nevertheless, the frontal 
arch terminated by two lateral appendages seems to have an exterior origin. This 
activity of calcareous secretion about each areola is very remarkable and tangential 
sections of the living Arachnopusia monoceros would be of great interest. 
The mucro is not at all constant; it is replaced in the nonovicellecl zooecia by 
a calcareous thickening bearing a cicatrix. Its development appears therefore 
according to rule to be in connection with the formation of a peristomie and with 
the passage of the eggs in the ovicell. 
Affinities . — This species differs from Arachnopusia ( Cribrilina ) terminata 
Waters in its zoarium, which is incrusting and not free; in its much smaller oral 
dimensions (0.15 mm. and not 0.25 mm. by 0.14 mm.) ; and in the presence of 
larger avicularia. 
The affinities of the Tertiary fauna of the American Gulf region are greatest 
with that of Europe, but in Arachnopusia we have a genus which has been observed 
in the fossil state only in the Southern hemisphere, chiefly in the Australian 
deposits. This single example is insufficient to prove communication with the 
Pacific of the American Tertiary Gulf, for the study of the Eocene deposits of the 
Pacific is still to be made. Arachnopusia monoceros Busk, 1854, was discovered 
recently in Florida waters at the Tortugas by Osburn. 
Occurrence . — Vicksburgian (Byram marl) : Byram, Mississippi (rare) ; one- 
fourth mile west of Woodward, Wayne County, Mississippi (rare). 
Holotype.— Cat. No. 64262, U.S.N.M. 
Genus FIGULARIA Jullien, 1886. 
1886. Figularia Jullien, Les Costulidies, Bulletin de la SociSte Zoologique de France, vol. 
77, p. 608. ( Figulina Levinsen, 1909.) 
Bibliography (Anatomical). — 1888. Jullien, Du testicule chez Lepralia figularis Memoires 
Societe Zoologique France, p. 2, pi. 10, figs. 1, 2. — 1902. IIarmer, On the Morphology of the 
Cheilostomata, Quarterly Journal Microscopical Science, vol. 46, p. 292, pi. 15, figs. 8, 9. — ■ 
1903. Norman, Notes on the Natural History of Bast Finmark, Annals Magazine Natural 
History, ser. 7, vol. 12, p. 98, pi. 9, fig. 7. — 1887. Waters, Bryozoa from New South Wales, 
Annals Magazine Natural History, ser. 5, vol. 20, p. 187. pi. 6, fig. 1. — 1889. Waters, Bryozoa 
from New South Wales, Annals Magazine Natural History, ser. 6, vol. 4, p. 5, pi. 1, figs. 6-9. 
