BBY020AN FAUNA OF VINCENTOWN LIMESAND 23 



The normal zooecia appear only at the summit of the fronds. 

 Their number is always less than that of the radicular zooecia. They 

 increase also from the base to the top, where they attain the dimen- 

 sions which we have given above and which are the largest that have 

 been observed. 



The regenerated zooecia are not rare ; but as they appear chiefly in 

 the intermediate zone between the normal and the radicular ones, 

 we may suppose that they are in course of transformation to radicular 

 cells. 



The avicularia remain small on the zooecia of the two lamellae, but 

 they are much developed and become large and salient on the lateral 

 zooecia; that is, on the zoarial margins, thus giving to the fronds 

 a very characteristic denticulated aspect, especially in the distal 

 zone of the normal zooecia. The ovicell is unknown. 



Biology. — For a long time it was difficult to interpret the curious 

 structure of these small fossils, but with increasing knowledge of 

 recent forms it is easy now to restore them in the imagination. They 

 were small bushes erect and attached in more or less numbers to a 

 chitinous stolon creeping over floating algae and living at some 

 distance from the bottom of the sea. They could increase in width 

 but not in height beyond a centimeter. We find therefore at this 

 period biologic structures very close to those observed in the Recent 

 seas. Also we find apparently justified our observations made in 

 1920 comparing the genus Stameiwcella with the recent genus Bugu- 

 laria Levinsen, 1909. 



Affinities. — This species is not a Planicellaria, for D'Orbigny's 

 genus is biserial, articulated at the top of the segments and not at 

 the base, and the avicularia are exclusively lateral. The cellular 

 structure is here indeed that of Stamenocella Canu and Bassler, 

 1920, the remarkable and very homogeneous genus that Voigt in 

 1930 has interpreted so well. The genus at present contains 2 species 

 from the Senonian, 2 from the Maastrichtian and 2 from the Danian 

 of Europe, 1 from the Vincentown marl of New Jersey, 1 from the 

 Eocene (Aquia) of Maryland, 1 from the Midwayan, 5 from the 

 Jacksonian, and 4 from the Oligocene (Vicksburgian) of the South- 

 ern States. In all, the colonies are free. 



Flustrella cylindrica Gabb and Horn has not been reidentified in 

 recent collections, but judged from the original illustration (see pi. 

 15, fig. 9) it may be the same as the present species. 



Occurrence. — Vincentown limesand: Common at Vincentown but 

 rare near Blackwoodstown, N.J. 



Cotype mid plesiotype.— ■U.S.N. M. Nos. 52612, 73874. 



