BRYOZOAN FAUNA OF VINCENTOWN LIMESAND 57 



Variations. — The superficial calcification or epicalcification is a 

 common phenomenon in all the cheilostomatous Bryozoa, and it has 

 been well known since the time of Milne Edwards, 1838. It is little 

 evident in the Membranipores where the frontal is chitinous, but it 

 is much more frequent in the derived Cribrimorphs, where it is still 

 more complicated by the proliferation of the oral spines. Lang, 1922, 

 has well shown its importance ; he designates as " connecting tissue " 

 or " secondary tissue " the calcareous deposits that invade the frontal 

 of many Cribrimorphs when they fill up the intercellular interspaces. 



On many of the old zooecia of Tricephalopora prolifera the costu- 

 lated area becomes scarcely visible and assumes the aspect of a simple 

 stellate pore, which is filled up in fossilization. Such zooecia are 

 rare, but it is probable that the drawing of Gabb and Horn was 

 based on this kind. We follow Lang, 1922, in the belief that Ulrich 

 and Bassler, 1907, were correct in their interpretation of the incom- 

 plete figure of Gabb and Horn. Moreover, in spite of the great abun- 

 dance of accumulated material in the National Museum, no other 

 species resembling this figure has been discovered. It is therefore 

 best to maintain the synonymy as noted above. 



The peristomie develops on the distal zooecium ; it is much devel- 

 oped in H aplocephalopora Lang, 1916, a superfluous genus in our 

 opinion, because the length of the peristomie is a trivial character. 



Affinities. — Tricephalopora having the avicularia oriented proxi- 

 mally are rare. We know only T. saltdeanensis Lang, 1916, from 

 the English Campanian, and the American species differs from it in 

 the presence of a single pseudospiramen. Nonovicelled zooecia are 

 rare, so that the species is well named. 



Occurrence. — Vincentown limesand: Not rare at Mullica Hill, 

 Vincentown, and near Blackwoodstown, N.J. Rare at Noxontown 

 Millpond and 2 miles southwest of Odessa, Del. 



Plesiotype.— U.S.N. M. No. T3924. 



TRICEPHALOPORA ACUTIROSTRIS, new species 



Plate 13, Figures 3, 4 



Description. — The zoarium is free, unilamellar. The zooecia are 

 indistinct, surrounded by a thick epicalcification, little elongated, 

 subelliptical ; the frontal bears eight very short costules arranged 

 at the bottom of an elliptical area and below an apertural bar simi- 

 lar to the costules; the peristomie, short but thick, begins with a 

 pseudospiramen placed above the costules and bears laterally two 

 long triangular, pointed, straight avicularia with a pivot. The 

 aperture is invisible and buried at the bottom of the peristomie. 

 The peristomice is terminal, semielliptical, transverse, irregular, 

 surrounded with a thick epicalcification. The ovicell is hypersto- 

 mial, not closed by the operculum, opening into the peristomie, 



