NORTH AMERICAN EARLY TERTIARY BRYOZOa. 
485 
Affinities. — One may follow, from the zoarial extremity, the formation of the 
avicularium. In the peristomial sinus first formed there develops a small avicu- 
larium which increases and is transformed in small, somewhat salient chambers. 
This species differs from Porella irregularis in the frontal granulations and 
the regular form of the zooecia. 
0 ceurrence. — Lower Jacksonian (Moodys marl) : Jackson, Mississippi (very 
rare). 
Holotype. — Cat. No. 64142. U.S.N.M. 
PORELLA CORONATA, new species. 
Plate 62, figs. 15-17. 
Description. — The zoarium incrusts bryczoa. The zooecia are somewhat elon- 
gated, little distinct, rather irregular; the frontal is convex and formed of a 
tremocyst with large pores in quincunx. The apertura is little visible at the base 
of a deep peristomie; the peristome is thin, salient, garnished with 1 to 5 small, 
round avicularia; the lyrula is very small and supports a median avicularium. 
The ovicell is large, transverse but little salient; it is formed of a large area finely 
porous and very fragile, surrounded by a little salient collar. The median avicu- 
larium is very little salient, opening outward and borne on a small lyrula. Some- 
times there are some small adventitious lateral avicularia. 
Measurements. — Peristomice \^ e 5*'^ mm ‘ 
[Ipe— 0.14 mm. 
Zooecia 
Lz= 0.60 mm. 
fe=0.30 mm. 
Variations. — The young zooecia (fig. 15) or marginal zooecia are separated 
by a prominent thread; their avicularium is buried in the peristomie, and the 
avicularia of the peristome are very small. • On the adult zooecia the avicularia of 
the peristome form a sort of crown around the apertura ; but their number is quite 
variable and the formation of the ovicell causes them to disappear (fig. 16) ; they 
have a pivot. The frontal of the ovicell is very fragile; its absence complicates 
still more the very irregular aspect of this species. 
Affinities.- — This species differs from Porella irregularis and Porella granulosa , 
which also have incrusting zoaria, in the presence of the avicularia on the peri- 
stome. 
Occurrence.- — Lower Jacksonian (Mood 3 ? s marl) : Jackson, Mississippi (rare). 
Middle Jacksonian (Castle Hayne limestone) : Wilmington. North Carolina 
(very rare) . 
Cotypes. — Cat. No. 64144, U.S.N.M. 
PORELLA DENTICULIFERA, new species. 
Plate 63. figs. 1-5. 
Description. — -The zoarium is bilamellar; the two lamellae are back to back 
and separable. The zooecia are indistinct ; the frontal is little convex and formed 
of a tremocyst, with pores enormous and little numerous. The apertura (in the 
interior) is semicircular and quite oblique with a proximal border somewhat con- 
