NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
131 
genus V aldemunitella. The form of the large interzooecial avieularia, the absence 
of the pivot, and the peculiar form of the mandibles are important arguments for 
the differentiation and the creation of a separate genus, but this is a study for 
the future. 
GRAMMELLA CRASSIMARGINATA Hincks, 1880. 
Plate 24, tigs. 13-15. 
1880. Membranipora crassimarginata Hxncics, General History of the Marine Polyzoa, I 
Madeiran Polyzoa, Annals Magazine Natural History, ser. 5, vol. 6, p. 71, pi. 9, fig. 1. 
1891. Membranipora crassimarginata , Hincks, General History of the Marine Polyzoa, 
Appendix, Annals and Magazine Natural History, ser. 6, vol. 8, p. 86. 
1898. Membranipora crassimarginata Waters, Observations on Membraniporidae, Jour- 
nal Linnean Society London, Zoology, vol. 26, p. 685, pi. 47, fig. 4. 
1900. Grassimarginatella crassimarginata Cantj, Revision des Bryozoaires du cretaee figures 
par d’Orbigny, Pt. 2, Cheilostomata, Bulletin Society Geologique de France, vol. 
28, p. 369. 
1903. Oochilina crassimarginata Norman, Notes on the Natural Plistory of East Finmark. 
Polyzoa, Annals and Magazine Natural History, ser. 7, vol. 11, p. 595. 
1909. Membranipora crassimarginata Norman, The Polyzoa of Madeira and neighboring 
Islands, Journal Linnean Society London, vol. 30, p. 287. 
1860. Membranipora lacroixii (?) Busk, Description of new Polyzoa, Quarterly Journal of 
Microscopical Science, vol. 8, p. 282. 
1861. Membranipora irregularis Busk, Description of new Polyzoa, Quarterly Journal of 
Microscopical Science, vol. 9 (n. s. vol. 1), p. 77, pi. 33, fig. 3 (not d’Orbigny). 
Description. — The zoarium incrusts pebbles, shells, foraminifera, and other 
bryozoa. The zooecia are elongated, distinct, oval, or elliptical with frequently a 
very small gymnocyst; the mural rim is very prominent, curved, thin at the top. 
enlarged at the base, finely granular. The opesium is elliptical, entire. The ovicell 
is globular, prominent, deeply excavated, and separated from the mural rim. The 
avicularium is interzooecial, as large as a zooecium; the mural rim is thick; the 
pivot is median and solid. 
Measurements.- — Opesia 
ho = 0.32-0.36 mm. 
lo= 0.20-0.22 mm. 
Zooecia 
fZs=0.50 mm. 
| la= 0.32-0.40 mm. 
V aviations. — Examples of total regeneration are numerous and manifest them- 
selves by their double mural rims. Figure 13 contains even a case of triple regen- 
eration. The ancestrula is rather small and of normal form. Closed zooecia per- 
forated by a small, round, medium pore, are located close to the ancestrula (fig. 15). 
The micrometric dimensions are identical with those of M embranipora crassi- 
marginata relying upon the figure given by Waters. The only difference from 
the recent species that we can cite is that in the latter the pivot of the avicularium is 
placed irregularly. On such a trifling difference we can not distinguish another 
species. 
GrammeMa crassimarginata exists to-day in the waters off the Madeira Islands. 
Its existence in the recent and ancient Gulf of Mexico is therefore very probable. 
Occurrence. — Middle Jacksonian (Castle Hayne limestone) : Wilmington. 
North Carolina (very rare). 
