286 



MOLLUSCOIDEA BRYOZOA 



SUB -KINGDOM V 



Family 6. Onychocellidae. Jullien, emend. 



Zoaria encrusting or erect, ramose, continuous, the branches more or less compressed and 

 bilaminar ; surface areolated. Zocecia usually hexagonal, their margins raised, the front 

 not entirely calcified. Opesial aperture of moderate size, generally semi-elliptical, sometimes 

 spreading below, in other cases sub-circular. Oral opening small, usually crescentic or semi- 

 circular. Ooecia inconspicu- 

 ous ; intercalated vicarious 

 avicularia generally present ; 

 special pores wanting. Cre- 

 taceous to Recent ; chiefly 

 Cretaceous. 



According as the specimens 

 were encrusting or erect, they 

 have been called Cellepora and 

 Membranipora ; or by others, 



vS^fflTll i|J^lfff^^ andS^s^r'S^ed^ccid- 



. A a a A * . I ing to Waters and others, all 

 of these names have boen 

 applied to a single species. 

 Onychocella angulosa, Reuss 

 sp. The zocecial characters 

 are comparatively simple and 

 uniform, and in most cases ' 

 the same as in the Cellariidae. 



On the other hand, species having a larger opesial opening than usual (Vilracella, etc.) evince 

 a decided resemblance to certain of the Membraniporidae. The systematic position of the 

 family therefore appeal's to be intermediate between the Cellariidae and Membraniporidae. 

 The relations of this family with the Palaeozoic Cryptostomata and Trepostomata are worthy of 

 further investigation. 



Onychocella (Jullien), Waters (Eschara, Flustrellaria, p.p., d'Orb. ; Cellepora, 

 i, Vincularia, etc., auct,), (Fig. 474). Zoaria encrusting or erect. Oral 



Onychocella 



Reuss sp. 

 Upper Eocene; 

 Northern Italy. 

 Surface, ao/j (after 

 Waters). 



Vincularia virgo, Hagw. Upper 

 Riigen. a, Portion of zoariuin, i/l 

 section ; c, Vertical section, enlarged. 



Cretaceous 



FIG. 476. 



Cumiilipora angulata, Miinst. Oligocene ; Doberg, near Blinde. A, Zoarium, natural size. B, Upper surface, 

 enlarged. C, Vertical section, enlarged (after Reuss). 



opening semi-circular or crescentic. Avicularian openings simple, oval ; the area in 

 which they are situated drawn out above. Cretaceous to Recent. 



Vibracella, Waters (Flustrellaria, p.p., d'Orb.) Differs from Onychocella in having 

 a larger aperture, which is often somewhat expanded below, and having vibracular 

 cells instead of avicularia. Cretaceous and Tertiary. 



1 Oumulipora, Miinst (Fig. 476). Zoaria irregularly massive. Zooecia partly 

 recumbent, partly erect, and placed one above the other, so that they appear to form 

 tabulated tubes. Tertiary. 



