NORTH AMERICAN EARRY TERTIARY BRYOZOA. 
581 
is transverse, globular, salient, and formed of a pleurocyst on an olocyst; it is 
hyperstomial, recumbent, and somewhat supported on the distal zooecium. 
Measurements .- — Apertura 
/m=0.06 mm. 
Za=0.12 mm. 
Zooecia 
/ 
Zs=0.60mm. 
lz~ 0.36-0.40 mm. 
Valuations .- — The mucro arises just in front of the orifice of the ovicell; its 
size depends strangely enough on the development of the ovicell. But its aspect 
is very irregular; sometimes it is erect (fig. 5). Sometimes it appears as depressed 
on the frontal (fig. 6). The greater part of the time the frontal appears smooth 
and the areolae are discernible only on perfect and very well cleaned specimens. 
Affinities . — This species differs from Perigastrella ovoidea in its small dimen- 
sions {Lz= 0.60 and not 0.80 mm.), in the absence of lyrula, in the apertura, and 
in its larger ovicell. 
It differs from Perigastrella trapezoidea, P. depressa , and P. rectilineata , 
whose aspect is equally smooth, in its more convex frontal, and especially in the 
great development of its peristomie and its labial mucro. 
Occui'rence . — Middle Jacksonian : Rich Hill, Crawford County, Georgia (rare) ; 
18 miles west of Wriglitsville, Johnson County, Georgia (rare). 
Cotypes. — Cat. Nos. 64198, 64199, U.S.N.M. * 
PERIGASTRELLA TRAPEZOIDEA, new species. 
Plate 73, figs. 8, 9. 
Description .— The zoarium incrusts bryozoa and shells. The zooecia are dis- 
tinct, somewhat elongated, irregularly hexagonal; the frontal is little convex, 
without distinct exterior peristomie, surrounded by a double line of very small 
areolae and formed of a finely granular pleurocyst. The apertura is trapezoidal , 
visible exteriorly, sometimes a little deformed by the mucro; the peristome is 
little salient; it bears six to eight spines on its distal part and a wide mucro erect, 
projecting in the form of a proximal lip. The ovicell is globular, salient, trans- 
verse, somewhat supported on the distal zooecium, finely granulated; it is hyper- 
stomial and recumbent. 
,, , , 7hz=0.06mm. 
Measurements . — Apertura < , n , . 
1 [la— 0.10 mm. 
Zooecia 
\L 
\lz 
2=0.50 mm. 
=0.40-0.50 mm. 
Variations . — The areolae and the frontal granulations are so small that the 
zooecia often seem nearly smooth. The tongue, which serves as a mucro, is gen- 
erally erect and very prominent just in front of the orifice of the ovicell, but 
often it is somewhat oblique and partially hides the apertura. 
Affinities . — This species differs from Perigastrella oscitans in its less elongated 
zooecia, its much smaller granulations, its ovicell with no distinct and visible 
olocyst, and in its very small, scarcely visible areolae. 
The difference from Perigastrella, maxilla is little apparent in superficial 
observation. It differs from it in its less elevated zooecia, its flatter frontal, its 
mucro never depressed on the frontal, and chiefly in the absence of an exteriorly 
visible peristomie. 
