NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
537 
guenza), of Belgium (Van den Broeck). Miocene of Australia (MacGillivray) 
and of New Zealand (MacGillivray). 
Plesiotypes. — Cat. No. 64316, U.S.N.M. 
METRARABDOTOS GRANDE, new species. 
Plate 98, figs. 11-15. 
Description. — The zoarium is free, arborescent, branched dichotomously in the 
same plane. The fronds are narrow, compressed, often twisted. The zooecia are 
elongated, distinct, fusiform, the frontal is convex, surrounded by areolae, and 
formed of a granular pleurocyst united to the olocyst. The apertura is oval and 
formed of a semilunar anter and of a broad, triangular rimule. in which a very 
small lyrula is placed. The peristome is hardly salient. The ovicell is endozooecial, 
enormous, with a frontal ornamented with larger, radial costules. 
M easurements- 
[4<a=0.10 mm. 
-Apertura { fa=al0mm . 
„ . [7,2=0.90 mm. 
Zooecia 7 no . 
[lz— 0.24 mm. 
Width of branches =3 to 5 mm. 
Variations. — The zoarium bears some tuberosities (fig. 15), partitioned in the 
interior, which serve perhaps as zoarial hydrostatic apparatus. 
The frontal walls of the zooecium are very thick (fig. 15), whereas the lateral 
walls are quite thin (fig. 14). 
This species is very abundant in the locality in Jasper County, Mississippi. 
It alone numbers many more specimens than all the others combined and constitutes 
almost alone the Cheilostome fauna of this locality. It occurs here in clay, which 
habitat it seems to prefer. This is also the case in the Metrardbdotos polymorphum 
Reuss, 1869, which lived in France in the clay of Gaas. 
We have attempted a restoration of this remarkable species; the zoarium must 
attain from 7 to 10 centimeters in length. 
Affinities. — This species differs from Me tra rabdo tos moniliferum Milne-Ed- 
wards, 1836, in its longer zooecia (Ls= 0.90 instead of 0.60 mm.), in the absence of 
small oral avicularia, and in a much larger zoarium, and with wider fronds (3-5 mm. 
instead of 2 mm.). 
Occurrence. — Vicksburgian (Marianna limestone) : Three miles southeast of 
Vosburg, Jasper County, Mississippi (very common). 
Vicksburgian (Red Bluff clay) : Seven and one-half miles southwest of Bladen 
Springs, Alabama (rare) ; Red Bluff, Wayne County, Mississippi (rare). 
Cotypes.— Cat. No. 64317, U.S.N.M. 
Genus WATERSIPORA Neviani, 1895. 
1895. Watersipora Neviani, Briozoi neozoici di alcune loeatita dTtalia, Bollettino della 
Societa Bomana per gli Studi Zoologici, pts. 2, 4, p. 231. 
The operculum is membranous or very slightly chitinous on the borders; it ex- 
hibits a chitinous axial band of a brown color, marking out from the rest of the 
operculum two lateral spaces, which are clearer and which correspond to the two 
