NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
443 
The ovicell is globular, salient, with tremopores analogous to those of the 
frontal (fig. 5) ; the zooecia which bear them have also an avicularium and a 
spiramen, but the latter invariably becomes closed and it does not appear in vertical 
sections (fig. 15). The ovicell is enormous, almost as large as the zooecia (fig. 15). 
If it contains only larvae, as is probable, their expulsion through a peristomice 
so small would present some difficulty. 
Tangential sections (figs. 13, 14) show numerous tremopores; the reticulations 
are not visible on account of the distance of the olocyst. 
Affinities. — This species differs from Metradolium labratulum in the absence 
of the large oral labrum. 
It differs from Metradolium parvirimulatum in the rarity of the zooecia with 
rimule-spiramen, in the much smaller dimensions of the peristomice (0.12 instead 
of 0.14 mm.), and in the constant presence of the large oral avicularium. 
Occurrence. — Middle Jacksonian: Wilmington. North Carolina (very com- 
mon) ; Eutaw Springs, South Carolina (rare) ; near Lenuds Ferry, South Caro- 
lina (common) ; Rich Hill, Crawford County, Georgia (common) ; 12 miles south- 
east of Marshall ville, Georgia (rare) ; 3J miles south of Perry, Georgia (very com- 
mon) . 
Cotypes. — Cat. No. 62596, U.S.N.M. 
METRADOLIUM PARVIRIMULATUM, new species. 
Plate 55, figs. 15-20. 
Description. — The zoarium is free, compressed, bilamellar; the fronds are flat, 
narrow, bifurcated; the lamellae are inseparable. The zooecia are little distinct; 
the frontal is convex, thick, formed of a tremocyst with numerous tubules. The 
apertura (interior) is semilunar; the peristomice is small, transverse; it bears a 
small unsymmetrical rimule-spiramen, one side being higher than the other; the 
peristomice of the zooecia with spiramen is wide, elliptical, transverse. There are 
two symmetrical, oral avicularia, of which one is much larger than the other; the 
latter is salient, elliptical, the beak turned toward the exterior. 
Measurements. — Peristomice 1 , . _ . 
, , . , te«=0.12mm 
(exterior) l L 
Zooecia Lz=0. 56— 0.60 mm. 
Variations. — The principal avicularium is very small (fig. IT), medium sized 
or very large (fig. 19). The zooecia with spiramen are rare; they are arranged 
in groups in the midst of the others. We are unable to learn what influence causes 
their formation. The ovicell is unknown. 
Affinities. — This species differs from Metradolium dissimile in the rarity of 
its zooecia with spiramen and its much smaller micrometric dimensions 
(lz=0. 56—0.60 and not 0.74— 0.76 mm.) . 
The specimens unprovided with zooecia with spiramen are difficult to dis- 
tinguish from Metradolium obliquum. It differs from it in its smaller micrometric 
dimensions (fe=0.56-0.60 and not 0.70-0.80 mm.) , in its much smaller rimule, 
nearly symmetrical and not oblique. 
