NORTH AMERICAN EARIA' 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. 



i/ifl.=0.06mm. . ( LsO.GOmm. 



Measurements. Apertura 7 /ooecia- 7 



l/a0.12 mm. I fe=0.36-0.40 mm. 



Variations. 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 Periijastrclla ovoid ea in its small dimen- 

 sions (Ls=O.GO and not 0.80 mm.), in the absence of lyrula, in the aperturn, and 

 in its larger ovicell. 



It differs from Periffastrella t)'(tj>ezoiih'<i, /'. th'/u'cssa, 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. 



Occurrence. Middle Jacksonian : Rich Hill. Crawford County, Georgia (rare) ; 

 18 miles west of Wrightsville, Johnson County, Georgia (rare). 

 es.Cat. Nos. 64198, 64199, TJ.S.KM. 



PERIGASTRELLA TRAPEZOIDEA, new species. 



Plate 73. figs. 8, 0. 



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. 



fA<z=0.06mm. . fZs=0.50mm. 



Measurements. Apertura 7 -,, Zooecia<, . n ,, 



[la=0.lO mm. [73=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 Periyastrella 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 P< ri<i<ixtrcUa ma.i'illa- is little apparent in superficial 

 observation. It differs from it in its less elevated zooecia, its natter frontal, its 

 mucro never depressed on the frontal, and chiefly in the absence of an exteriorly 

 visible peristomie. 



