NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
445 
METRADOLIUM GRANDE, new species. 
Plate 55, figs. 12-14. 
Description. — The zoarium is free, bilamellar, erect; the fronds are dicho- 
tomous, foliaceous or subcylindrical ; the two lamellae are inseparable. The zooecia 
are very large, elongated, indistinct laterally ; the frontal is convex, thick, formed 
of a tremocyst with large pores. The peristomice is large, elongated; the rimule- 
spiramen is large, rounded. The oral avicularium is large, transverse adjacent to 
the peristomice or placed in the peristomie. 
Measurements. — Peristomice ihpe— 0.35-0.45 mm. r . . [Zs=0.90-1.00 mm. 
(exterior) 0.25-0.40 mm. ^ ooecia | Z5’=0.50 mm. 
Affinities. — When the avicularium is exterior the rimule-spiramen is quite well 
formed (fig. 13) ; when it is hidden in the peristomie the rimule becomes very 
irregular and deeper. It is the lengthening of the tubules of the tremocyst which 
increase and deform the peristomice and augment the external dimensions of the 
zooecia. 
This species differs from Metradolium transversum in its large rimule, its 
elongated and nontransverse peristomice (hpe= 0.35 and not 0.15 mm.) and its 
large tremopores. 
It differs from M ' etradolium sulciferum in the absence of frontal sulci and its 
smaller general micrometric dimensions. 
Occurrence. — Middle Jacksonian: Near Lenuds Ferry, South Carolina (very 
rare) ; Rich Hill, Crawford County, Georgia (rare) ; Eutaw Springs, South Caro- 
lina (rare) ; one-half mile southeast of Georgia Kaolin Company Mine, Twiggs 
County, Georgia (rare). 
Jacksonian (Zeuglodon zone) : Bluff on south side of Suck Creek. Clarke 
County, Mississippi (very rare). 
Cotypes. — Cat. Nos. 64116, 64117, U.S.N.M. 
METRADOLIUM CONVENIENS, new species. 
Plate 56, figs. 16-21. 
Description. — The zoarium is free, bilamellar, erect; the fronds are foliaceous, 
fiat, or undulated, branching; the two lamellae, back to back, are inseparable. The 
zooecia are elongated, little distinct laterally; the frontal is convex, thick; it is 
formed of a tremocyst with small tubules arranged in quincunx, placed on a very 
thin olocyst with small corresponding pores. The apertura is subround ; the peri- 
stomice is very elongated, elliptical ; the rimule-spiramen is more or less visible and 
always symmetrical. The ovicell is globular, little salient, ornamented with tremo- 
pores similar to those of the frontal; its peristome is transverse in the form of a 
lunar-crescent; it is hyperstomial, very large, and opens largely into the peristomie. 
Near the peristomice there are two elliptical avicularia, replaced often by a single 
larger and more salient one. 
