350 



MOLLUSCOIDEA— BRYOZOA 



PHYLUM V 



immersed, their horders elevated. Orifice rounded or semi-elli'ptical^ situated more or less 

 in advance of the depressed front. Small vihracular cells usually present. Cretaceoiis 

 to Becent. 



LunuUtes Lamx. (Fig. 512). Zooecia arranged in series radiating from the 

 centre and bifiircating as they advance toward tlie border. Vibracular cells usually 

 elongate, lying in linear series between the rows of zooecia. Very abundant in the 

 Upper Cretaceoiis and Tertiary ; also Recent. 



Vibracular cells wanting. Zoojcia equal, 

 hexagonal, not arranged in radiating series. 

 Cretaceous. 



Selenaria Busk. Cretaceous to Recent. 



Stichopora Hagw. emend. Busk. 





Fig. 513. 

 Memhraniporella 

 ahbotti (G, and H.). 

 Cretaceous ; N.J. 

 Zooecia highly mag- 

 nified (after Gabb 

 and Hörn). 



Fig. 514. 



Cribrilina heermanni 

 (G. and H.). Post-Plio- 

 cene ; Santa Barbara 

 Co.,Cal. Zooecia highly 

 magnifled (after Gabb 

 and Hern). 



Family 7. Oribrilinidae Hincks. 



Zoaria encrusting or erect. Zooecia having 

 the front wall more or less fissured, or traversed 

 by radiating furrows. Cretaceous to Recent. 



Memhraniporella Smitt (Fig. 513). Zoaria 

 encrusting or rising into free foliaceous ex- 

 pansions, sometimes consisting of superim- 

 posed layers. Zocecia closed in front by a 

 number of flattened calcareous ribs more or less Consolidated centrally. Cretaceous 

 to Recent. 



Grihrilina Gray (Fig. 514). Zoaria usually encrusting. Zooecia having the 

 front more or less occupied by radiating or transverse rows of punctures, each row in 

 a furrow ; orifice semicircular or sub-orbicular, Cretaceous to Recent. 



Family 8. Onyohocellidae JuUien (emend.). 



Zoaria encrusting or erect, ramose, continuous, the hranches more or less compressed 

 and hilaminar ; surface areolated. Zooecia usually hexagonal, their margins raised, 

 the front not entirely calci- 

 fied. Opesial aperture of 

 moderate size, generally semi- 

 elliptical, sometimes spread- 

 ing helow, in other cases suh- 

 circular. Oral opening 

 small, usually crescentic or 

 semicircular. Ooecia in- 

 conspicuous ; intercalated 

 vicarious avicularia gener- 

 ally present; special pores 

 wanting. Jurassic to Re- 

 cent ; chiefly Cretaceous. 



Fig. 515, 



Onychocella angu- 

 Zosa(Reuss). Upper 

 Eocene ; Northern 

 Italy. Surface, 20/^ 

 (after Waters). 



Fig. 516. 



Vincularia virgo Hagw. Upper Cretaceous ; 

 Rügen. a, Portion of zoarium, i/^. h, Cross- 

 section. c, Vertical section, enlarged. 



Onychocella JuUien {Es- 

 chara, Flustrellaria, p.p., 

 d'Orb. ; Cellepora, Mem- 

 hranipora, Vincularia, etc. 

 auct.) (Figs. 515, 516). Zoaria encrusting or erect. Oral opening semicircular or 

 crescentic. Avicularian openings simple, oval ; the area in which they are situated 

 drawn out above. Jura of Normandy, and Cretaceous to Recent. 



