BKYOZOAN FAUNA OF VINCENTOWN LIMESAND 45 



It is the same with C oscino pleura digitata, for on its innumerable 

 fragments we have discovered for the greater part the encrusting 

 species herein described. However, as the incrustation is never very 

 thick, we must conclude that the sedimentation was rapid and that 

 all these fragments were rapidly covered and fossilized. 



Occurrence. — Vincentown limesand: Timber Creek, Mullica Hill 

 (Gabb and Horn), Vincentown, and near Blackwoodstown, N.J. 

 (very common). 



Geological distribution. — Bryozoan beds of Aquia formation 

 (Eocene) : Upper Marlboro, Md. 



Plesiotgpes.—XJ.S.NM. Nos. 63786, 73934. 



Suborder Ascophora Levinsen 



Family LAGYNOPORIDAE Lang, 1916 



Genus LAGYNOPORA Lang, 1916 



LAGYNOPORA AMERICANA, new species 



Plate 10, Figi-be 6 



Description. — The zoarium encrusts fragments of shells. The 

 zooecia are distinct, separated by a deep furrow, elliptical, much 

 elongated and quite convex; the frontal bears 6 or 7 pairs of flat, 

 smooth, scattered costules joined together only on the median longi- 

 tudinal axis; the apertural bar is thick, convex, and bears rarely a 

 small median process. The aperture (visible exteriorly) is semi- 

 elliptical, transverse, irregular; the distal peristome is thin, little 

 salient, and bears two large hollow lateral spines. The ovicell is 

 hyperstomial, buried in the distal zooecium not closed by the oper- 

 culum, globular, smooth; its orifice is placed below the level of the 

 apertural bar so that the operculum moves in a locella. Avicularia 

 (?) sporadic and very rare. No dietellae. 



Measurements. — 



„ . [Zs = 0.65 mm. . . . . (A#=0.07 mm. 



Zooecia K ._., Apertura (exterior) i 7 „ _, „ 



|?2=0.35 mm. L v ' |Z<2=0.15 mm. 



25 zooecia in 4 sq. mm. 

 Structure. — The structure is that of M embraniporella, and it is 

 easy to restore the chitinous organs that have disappeared through 

 fossilization. The arrangement of the orifice of the ovicell is signifi- 

 cant; it is not placed above the convex apertural bar but below it; 

 the opercular valve, not being able to pass beyond the latter, moves 

 therefore under it in a kind of locella. Moreover, as it is necessarih T 

 attached to the ectocyst, the latter can be situated only under the 

 frontal costules in the interior itself of the zooecium. The costules 

 therefore belong to the kind we have termed pericystic. This is a 



