EAELY TERTIARY CHEILOSTOME BRYOZOA. 37 



convex. The ovicell is endozooecial and exteriorly is prominent and 

 transverse ; it is formed of two calcareous deposits ; the outer one is 

 incomplete and leaves two lateral cicatrices in the form of a cross. 

 The avicularia are interzooecial and are elongated, spatulate, per- 

 forated by a long slit and generally without pivot. 



^ ,. ^ f ha=0.09 mm. 



Measurements. — Ordmary aperture N^__qj^2 mm. 



„ . „ , , f7i«=0.10mm. 



Ovicelled aperture 7 ^^^ 



^ l?a=0.13 mm. 



. fZs=0.50-0.60mm. 

 Zooecia ' ^^p, ^ „^ 



[?s=0.25-0.3o mm. 



This species must not be confounded with any species of the genus 

 Figularia JuUien, which is provided with a hyperstomial ovicell. 



Occurrence. — Middle Jacksonian (Castle Hayne limestone) : Wil- 

 mington, North Carolina (rare). 



Type.— Cixi. No. 62588, U.S.N.M. 



Family ACROPORIDAE Canu, 1913. 



The zooecia are indistinct and their frontal is thickened. The 

 ascopore, perforating the frontal, opens into the zooecia below the 

 operculum. The hyperstomial ovicell is deeply immersed and in- 

 visible exteriorly. The apertura is buried at the bottom of a long 

 peristomie. There are some frontal avicularia and some peristomial 

 avicularia. 



The characteristics of this family are not yet sufficiently studied; 

 the recent specimens are rare and the sections made of the fossil 

 forms are often difficult to interpret. 



We are able to distinguish the principal genera only by the nature 

 of their frontal. 



Following the Membraniporae, these are the most ancient Cheilos- 

 tome fossils known. 



The genera of this family and their range are indicated below: 

 k\\ are represented in the early Tertiary of North America. 



Acropora Reuss, 1869. Maastrichtian-Recent. 



Gastropella^ new genus. Midwayan-Jacksonian. 



Pachytheca Canu, 1913. Campanian-Midwayan. 



Beisselina Canu, 1913. Cenomanian-Jacksonian. 



GASTROPELLA, new genus. 



{Gaster, stomach; ope, small opening.) 



An Acropora having a smooth frontal garnished laterally with 

 areolae. 

 Genotype. — Gastropella ventricosa, new species. 

 Range. — Midwayan-Jacksonian. 



