AKT.22. CYCLOSTOMATOUS BRYOZOA — CANU AND BASSLER. 41 



We have been able to secure ovicells of this remarkable species 

 and have chosen the two which differ the most for illustration. They 

 are similar to the ovicell of ^tathmeyora {Bisidmonea) gahhiana. 

 Ulrich and Bassler, 1907. Most of the tubes in lines are aborted, 

 but there persists always at least one which opens above the con- 

 vexity of the ovicell. One of the tubes is perhaps the oeciostome, 

 but we have not cared to dissect our specimens. As in the American 

 species, there is a simultaneity in the calcification of the ovicell and 

 all the peristomies of the tubes. 



Geological distnhution. — Cretaceous: Danian of Denmark; Seno- 

 nian of Switzerland. 



Family DIAPEROECIIDAE Canu, 1918. 



1918. DiaperoccUdae Canu, Les ovicelles des Bryozoaires Cyclo.stomes, 

 Bulletin Soci6t^ G^ologique de France, ser. 4, vol. 16, p. 329. — 1920. 

 Canu and Basslek, North American Early Tertiary Bryozoa. Bull. 

 106, U. S. National Museum, p. 738. 



The ovicell is formed after the calcification of the distal tubes. 

 It is an irregular, subglobular elevation placed among many tubes, 

 which are not disarranged from their respective position but project 

 on the ovicell itself. The oeciostome is submedian transverse, sali- 

 ent, often isolated, generally proximally directed. 



The genera at present referred to this family are Diaperoecia 

 Canu, 1918, Diplosolen Canu, 1918, Lehythionia Canu and Bassler, 

 1920, Crisulipora Robertson, 1910, Desmediaperoecia Canu and Bass- 

 ler, 1920, and Stigmatoechos Marsson, 1887. 



Genus DIAPEROECIA Canu, 1918. 



1918. Diaperoecia Canu, Les ovicelles des Bryozoaires Cyclostomes, Bulle- 

 tin Soci^tg G^ologique de France, ser. 4, vol. 16, p. 329. — 1920, Canu 

 and Bassleb, North American Early Tertiary Bryozoa. Bull. 106, 

 U. S. National Museum, p. 740. 



DIAPEROECIA POLYSTOMA Roemer. 1839. 



Plate 7, fig. 11. 



1839. Cellepora polystoma Roemer, Die Versteinerungen des norddeutschen 

 Oolithen-Gebirges Hannover, (1836) Nachtrag, p. 14, pi. 16, fig. 6. 



1899. Berenicea polystoma Gregory. Catalogue of the Cretaceous Bryozoa 

 in the British Museum, vol. 1, p. 10, pi. 5, fig. 5; pi. 6, fig. (Bibliog- 

 raphy). 



This little species is not rare. One recognizes it quite often in the 

 Neocomian fossils in France, Germany, and Switzerland. More re- 

 cently Gregory claimed to have rediscovered it in the Coniacian at 

 Chatham, England, but he did not figure the ovicell. 



Our ovicelled specimen indicates that this species is a Diaperoe- 

 cia: unfortunatelv the oeciostome is not visible. 



