494 R. M. Br y done — New Cretaceous Polyzoa. 



anterior lip of the secondary aperture, and the higher angle of rise of 

 the anterior lip of the secondary aperture and the low angle of the 

 plane of the secondary aperture when no ooecium is present. The 

 sum of these differences is not over-convincing, hut I think it is just 

 sufficient to support a specific distinction which marks a substantial 

 difference both in horizon and area. 



The species occurs freely at the top of the (restricted) zone of 

 A. quadratus at Bramford, Suffolk, and there are indications that it 

 occurs rarely in the Weybourne and Trimingham Chalks. 



Mehbeanipoeella stjbcastettm, sp. nov. (PI. XXXII, Fig. 6.) 



Zoarium unilaminate, adherent. 



Zocecia small, average length -6 mm.; primarily they are of the 

 usual type, with low, slightly arched side walls, arched front walls 

 pierced by four or five pairs of short, narrow, radiating slits, and 

 a semicircular aperture; in the secondary stage there is the usual 

 formation of a secondary aperture from a denticle appearing on the 

 posterior lip of the primary aperture and from the uprising of the 

 latter's sides; the side walls rise and thicken as usual and fuse with 

 one another and the margin of the secondary aperture and the 

 ooecia so as to form a broad network, enclosing and raised above the 

 front walls and encroaching on them so as to partly or even wholly 

 cover up the slits, and featureless except for (1) the secondary 

 aperture, which is more or less horseshoe-shaped with a strong 

 tendency to a small denticle on the posterior lip, and the anterior lip 

 formed mainly by the edge of the ooecium, which though incon- 

 spicuous is very regularly present ; (2) the apertures on the side 

 walls of small avicularia merged in the general mass and present 

 fairly regularly at the lower corners of the secondary aperture and 

 also irregularly elsewhere ; the edges of the secondary aperture run 

 a little way up the ooecium, but do not apparently unite across it. 



Ooecia large in proportion, rather flatly globose, with aperture only 

 slightly cut back. 



This species is in nearly every respect an ill-defined ancestor of 

 Membraniporella castrum, Bryd., 1 the latter is readily distinguishable 

 by its more numerous and conspicuous slits in the front wall, and its 

 curious cavity in the posterior lip of the secondary aperture, which is 

 indicated in the original figure, though not referred to in the original 

 description, and is very useful for rapid diagnosis. A figure of an 

 admirable specimen of M. castrum is given for comparison. M. sub- 

 castrum occurs rather scantily in the zone of Marsupites and the 

 subzone of E. scutatus var. depressus in Sussex. Specimens are 

 usually very obscure. 



Membeanipoeella Gabina, sp. nov. (PI. XXXII, Fig. 8.) 



Zoarium unilaminate, adherent. 



Zocecia narrow, but rather long, average length - 75mm. ; the side 



walls are almost common, only faint traces of a separate origin being 



left, and are wide, especially at the ends, and the arched front wall 



appears to be laid on them and to overlap their edges considerably at 



1 Geol. Mag., 1909, p. 398, PI. XXII, Figs. 4, 5. 



