THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE VL VOL. V. 



No. I.— JANUARY, 1918. 



CDlRXGrXlSr .A.JL. .A.E?,TICI-.EiS_ 



I. — Notes on new or imperfectly known Cretaceous Polyzoa. 

 By E. M. Brydone, F.G.S. 



(Continued from the November Number, ^. 4:96.) 

 (PLATE I.) 



VICxiKIOITS avicularia, that is to say avicularia substantially as 

 large as zooecia, have rarely been iigured among the Cretaceous 

 Cribrilinidfe, the only good instances I call to mind being Escharipora 

 incrassata, D'Orb./ Memhraniporella ( Cribrilina) Falcohurgensis^ Perg.,- 

 the illustration of which shows a clear case, although no reference is 

 made to it in the text, and Cribrilina ostreicola, Bryd.^ They are 

 not, however, by any means so rare as this might suggest, and the 

 four following species are probably not the only instances which will 

 ultimately be added from the English Chalk. 



Membraniporella Altonensis, sp. nov. (PI. I, Figs. 1, 2.) 



Zoarium unilaminate, adherent. 



Zooecia small, average length '45 to '5 mm. (exclusive of 

 ooecium) ; side walls arched slightly inwards, front walls arched, 

 arising without apparent break from the edges of the side walls and 

 pierced by six pairs of radiating slits reaching from the edges nearly 

 to the middle line ; aperture semicircular, very simple, the posterior 

 lip being apparently unthickened. 



Ocecia occurring very regularly, helmet-shaped, with apertures 

 cut well back. 



Avicularia vicarious, with vaulted blister-like external walls; 

 apertures shaped like a thermometer tube, with round bulb and 

 straight stem ; there is no raised rim round the bulb, but as it passes 

 into the stem rims arise rapidly on either side and enclose the whole 

 length of the stem, opening out into a small circle at the anterior 

 end to admit a narrow internal front wall; as the surface of the beak 

 is horizontal it stands out increasingly as the surface of the external 

 wall descends anteriorly. Sometimes the beak is covered by an 

 imperforate membrane. This species occurs very rarely in the zone 

 of H. planus near Alton, Hants. 



Membraniporella Shawfordensis, sp. nov. (PI. I, Figs. 6, 7.) 

 Zoarium unilaminate, adherent. 



Zooecia of medium size, average length "58 to "62 mm. ; the normal 

 surface is obviously largely secondary ; I have not seen any certain 



1 Pal. Cret. Franc, v, p. 223, pi. 685, figs. 2, 3. 



- Bull. Soc. Beige Geol., 1893, p. 176 et seq., text-fig. 7. 



- Geol. Mag., 1909, p. 399, PL XXIII, Figs. 1, 2. 



decade VI. — VOL. v. — NO. I. 1 



