NORTH AMERICAN EARLY TERTIARY BRYOZOA. 313 



./ui=0.l5mm. . (3=0.65-0.72 mm. 



Measurements. Aperture { 7 . Zooecia< 7 AOC 



i '" n i P. rv.rm |/s=:t).o5 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 nonovicelled 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.CvA. No. 64262, U.S.N.M. 



Genus FIGULARIA Jullien, 1886. 



18S6. Figvlaria JULLIEN, Les Costulidies, Bulletin de la Society Zoulogique de France, vol. 



77, p. 608. (Figulina Levinsen, 1909.) 



HibUograiilty (Anatomical). 1888. JULLIEN, Du testicule chez Lepralia figularis Memoires 

 SociSte Zoologique France, p. 2. pi. 10, figs. 1, 2. 1902. HASMER, 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 East Finmark. Annals Magazine Natural 

 History, ser. 7, vol. 12, p. 98, pi. 9, fig. 7. 1887. WATERS, Bryuzna I'rom New South Wales, 

 Annals Magazine Natural History, ser. 5, vol. 20, p. 187. pi. G. fig. 1. 1889. WATERS, Bryozoa 

 from New South Wales, Annals Magazine Natural History, ser. 6, vol. 4, p. 5, pi. 1, figs. 6-9. 



