BRYOZOAN FAUNA OF VINCENTOWN LIMESAND 49 



The species differs from DistanseschareUa pumila Gabb and Horn, 

 1862, in its slightly larger micrometric dimensions (especially in 

 width), in the absence of frontal tuberosities, and in the wider, less 

 numerous, and more scattered costules. It is, moreover, the largest 

 species of this group characterized by verj^ small zooecia. There are 

 no fundamental differences from Gabb and Horn's species, the same 

 aperture, the same ovicell, and the same zooeciules. 



In this group the aperture constant in form and dimensions was 

 necessarily closed by an opercular valve opening exteriorly, chitinous 

 and articulating on the two cardelles. Since the valve is attached 

 to the ectocyst, the latter covers the frontal as in the greater part 

 of the Kecent Cribrimorphs. It has therefore a general structure 

 much more evolved and complicated than that of Lagynopora pre- 

 viously studied. 



Occurrence. — Vincentown limesand: Vincentown, N.J.,and Noxon- 

 town Millpond, Del. (very rare). 



Eolotype.—U.S.'NM. No. 73297. 



Genus PLIOPHLOEA Gabb and Horn, 1862 



PLIOPHLOEA SAGENA Morton, 1834 



Plate 11, Figures 1-5 



1S34. Flustra sctffena Morton, Synopsis of the organic remains of the Cretaceous 



group of the United States, p. 79, pi. 13, fig. 7. 

 1921. Pliophloea sagena Lang, Catalogue of the Cretaceous Bryozoa in the 



British Museum, vol. 3, pt. 1, p. 189, text fig. 89, pi. 6, fig. 4 (bibliography). 



Description. — The zoarium is free, multilamellar; the first lamel- 

 lae are placed back to back and inseparable. The fronds are more 

 or less broad, compressed, flat or undulated, bifurcated in the same 

 plane. The zooecia are distinct, separated by a deep furrow, much 

 elongated, elliptical or oval; the frontal is little convex and formed 

 of 6 or 7 pairs of closely arranged costules separated by a row of 

 very small lacunae; the costules are flat, irregular in width, often 

 decorated with a row of punctations; the apertural bar is wide, 

 convex, and forms a crescent around the poster. The aperture is 

 semicircular; two false cardelles placed very low, in the vicinity of 

 the proximal border, separate a large anter from the poster; the 

 distal peristome is thin, salient, and bears small spines. The ovi- 

 cell is hyperstomial, deeply embedded in the distal zooecium, closed 

 by the operculum, large, convex, carinated, mitriform. A pair of 

 auriform vibracula always accompany each aperture; they are sym- 

 metrically placed on each side of the aperture and prolong the 

 apertural bar. The zooecia of the exterior lamellae are smaller 

 than those of the inner lamellae of the same zoarium. 



