48 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ut 



Genus MESENTERIPORA Blainville, 1834 



MESENTERIPORA MARGINATA D'Orbigny, 1853 



Plate 6, fig. 3 



1899. Diastopora marginata Gregory, Catalogue of the Cretaceous Bryozoa in 

 the British Museum, vol. 1, p. 137. (Bibliographj^ and occurrence.) 



Measurements. — Diameter of aperture, 0.14-0.16 mm.; diameter 

 of peristome, 0.22 mm.; diameter of tubes, 0.27 mm.; distance of 

 peristomes, 2 mm.; separation of peristomes, 0.64-0.72 mm. 



Structure. — We provisionally place this beautiful species next to 

 Nematifera because of the presence of separating salient threads, but 



we have not yet been able to 

 discover the ovicell. More- 

 over, the transverse section is 

 of a type entirely special. 

 There is no basal lamella, 



Fig. 21. — Mesenteripora marginata D'Orbigny, 18 53. . , . i, j.i i ii 



Transverse section, X 16. Lower Cretaceous (Val. ^rid although the lamellar 

 angian): Sainte-Croix, Switzerland ZOarium haS tWO sidcS they 



are not formec) by two lamellae placed back to back. The tubes 

 are polygonal, with thin walls arranged in quincunx and confused. 



Occurrence. — Lower Cretaceous (Valangian) : Sainte-Croix (Vaud), 

 Switzerland, and Villers-le-lac (Jura), France. 



PlesiotyiJes.— Cat. No. 69897, U.S.N.M. 



Family PLAGIOECIIDAE Canu, 1918 



Genus NOTOPLAGIOECIA Canu and Bassler, 1922 



The ovicell is an irregular convex capsule, replacing many peri- 

 stomes. The tubes are short, club-shaped, with moniliform walls 

 thickened at the extremities. The gemmation is dorsal. There is 

 no basal lamella. 



Provisional genotype. — Notoplagioecia faringdonensis Canu and 

 Bassler, 1922. 



Range. — Cretaceous (Aptian, Coniacian). 



NOTOPLAGIOECIA FARINGDONENSIS Canu and Bassler, 1922 



Plate 5, figs. 3-5 



Description. — The zoarium is free, cylindrical or compressed. The 

 tubes are indistinct, very little convex, smooth. The peristomes are 

 orbicular, thin, arranged in quincunx or in transverse rows. The 

 zone of growth is an elevated cone. The ovicell is an irregular sack 

 covering many adjacent tubes. 



