BRYOZOAN FAUNA OF VINCENTOWN LIMESAND 59 



spiramen. It differs from Haplocephalopora unieeps Lang, 1910, 

 from the Danian of Faxe in its shorter dimensions, in its transverse 

 and longer avicularia, and in its shorter peristomie, which is en- 

 larged distally. 



Occurrence. — Vincentown limesand : Very rare at Vincentown, 

 N.J., and at Noxontown Millpond, Del. 



Holotype.— U.S.N.M. No. 73925. 



Genus POLYCEPHALOPORA Lang, 1916 



POLYCEPHALOPORA BIROSTRATA, new species 

 Plate 14, Figures 1-3 



Description. — The zoarium encrusts shells and C oscinopleura and 

 may attain 2 cm in diameter. The zooecia are distinct, separated 

 by a shallow furrow, elongated, elliptical or oval; the frontal is 

 convex, formed of 12 to 16 costules and of an orbicular, wide median 

 area of fusion; the costules are decorated with a distal pelma and a 

 proximal pelma; the apertural bar is wide, convex, arched, united 

 with the distal peristome. The apertura is large, terminal, oblique 

 suborbicular ; the distal peristome is thin, little salient, decorated 

 with small spines. The ovicell is hyperstomial, not closed by the 

 operculum, buried in the distal zooecium, large, globular, elongated, 

 oval, smooth. Each zooecium bears laterally two large avicularia, 

 symmetrically arranged below the aperture; the} 7 are elliptical, 

 salient, with a pivot, with beak rounded and oriented distally. 

 The primoserial avicularia are oriented transversely. The ances- 

 trula is very small, membraniporoid, and thin, with two large, salient 

 avicularia. 



Measurem ents. — 



„ . \Lz = 0.6-0.65 mm. . \ha= 0.15 



ZooeciaJ /s = 35 _ a4 mm Apertura |^ =() lg 



\ha= 0.15 mm. 

 mm. 

 14 zooecia in 4 sq. mm. 



Variations. — The ancestrular zooecia are very small; their di- 

 mensions are scarcely half the normal zooecia; but in all their 

 characters they are absolutely analogous. 



The ovicells are buried in the distal zooecium in which the num- 

 ber of costules is thus diminished. 



Lang, 1922 (p. 43, fig. 15), has well schematized the formation 

 of the wide median area of fusion, but here the pelmatidia are 

 replaced by the pelma. It is, moreover, difficult to differentiate 

 these two kinds of cicatrices ornamenting the costules. 



The theoretical order of the avicularia is often altered by the 

 presence of ovicells and by that of the primoserial avicularia. In 

 appearance the avicularia seem to be irregularly scattered, but in 



177635—33 5 



