NORTH AMERICAN EARLY TERTIARY BRYOZOA. 311 



., . j. =. 



Measurements. Ordinary aperture , 



\ 7(7=0.11 mm. 



f ha=O.W mm. 



~ . j 



Ovicelled aperture^ ., 



l=0.13 mm. 



. [7",s=0.50-0.60mm. 

 ZooeCia U=0.25-0.35mm. 



Affinities. The discovery of a member of the Cribrilinidae provided with an 

 endozooecial ovicell is very important, as it indicates clearly that the structure of 

 the frontal has no connection with the various organs (ovarian) of the polypide. 

 At the same time the presence of the costules does not imply the muscular system 

 of the Anasca, since the form of the aperture indicates a characteristic compen- 

 satrix of the Ascophora ; this frontal has no connection with the hydrostatic system. 



The costular structure has no special function, being only a decoration or, 

 to be exact, an adaption for a particular purpose, and it can not be employed to 

 characterize a natural family. 



This species must not be confounded with any species of the genus Figularia 

 Jullien, which is provided with a hyperstomial ovicell. 



Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 

 Carolina (rare). 



Holotype.Cat. No. 62588, U.S.N.M. 



Genus ARACHNOPUSIA Jullien, 1886. 



' Bibliography (Anatomical). 1881. HINCKS, Contribution! toward a general History of the 

 Marine Polyzoa, Annals Magazine Natural History, ser. 5, vol. 8, p. 57, pi. 3, fig. 6. 1884. HINCKS, 

 Contribution toward a general History of Marine Polyzoa, Annals Magazine Natural History, 

 ser. 5, vol. 4, p. 129, pi. 8, fig. 5. 1884. BUSK, Report on the Scientific Results of the Voyage 

 of the Challenger, pt. 1, Cheilostomata, vol. 10, pt. 30, p. 133, pi. 19, fig. 8. 1887. WATERS, 

 Bryozoa from New South Wales, North Australia, Annals Magazine Natural History, ser. 5, 

 vol. 20, p. 187, pi. 6, fig. 7. 1SSS. JULLIEN, Mission scientific du Cap Horn, vol. 6, Zoology, 

 Bryozoaires, p. 63, pi. 3, figs. 8, 9. 1906. WATERS, Bryozoa from Chatham Island, Annals 

 Magazine Natural History, ser. 7, vol. 17, p. 16, pi. 1, fig. 11. 



The cribriform area is formed by the coalescence of hollow branched spines 

 attached to the lateral walls. The lacunae are concentrically arranged and semi- 

 lunate with an interior denticule. The opercular valve is membranous. The ovicell 

 is hyperstomial and opens into a small peristomie above the operculum ; it is closed 

 by a special operculum and is formed by a double calcareous deposit. The lateral 

 walls have septular disks with 1 to 3 pores; the distal walls bear only septules; 17 

 tentacles. 



Genotype. Arachnopusia (Lepralia) monoceros Busk, 1854. 



Range. Vicksburgian-Recent. 



ARACHNOPUSIA VICKSBUKGICA, new species. 



Plate 85, figs. 1-3. 



Description. The zoarium incrusts shells. The zooecia are distinct, separated 

 by a furrow, at the bottom of which there are some small, elliptical, wide pores; 



