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. Zowcia 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.  Owcta inconspicu- 
ous; intercalated vicarious 
avicularia generally present ; 
special pores wanting. Cre- 
taceous to Recent ; chiefly 
Cretaceous. 
b Cc 
According as the specimens 
were encrusting or erect, they 
have been called Cedlepora and 
Membranipora ; or by others, 
Eschara, Vincularia (Fig. 475), 
and Biflustra. Indeed, accord- 
ing to Waters and others, all 
of these names have been 
applied to a single species, 
Onychocella angulosa, Reuss 

Fic. 474. 
Onychocella angu- 

los1, Reuss sp. Fic. 475 ki = 
Upper Eocene; yea eee sp. The zoccial characters 
omer ee _ i eae Bua, HaeM _U Ppe ae ee are comparatively simple and 
Surface, 29/; (after tigen. a, Portion of zoarium, 1/;; b, Cross- “pf aa 1) eee 
Waters). section ; c, Vertical section, enlarged. uniform, and in most cases 
the same as in the Ced/ariidae. 
On the other hand, species having a larger opesial opening than usual (/ilracella, etc.) evince 
a decided resemblance to certain of the Membraniporidae. The systematic position of the 
family therefore appears 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 (Hschara, Flustrellaria, p.p., @Orb.; Cellepora, 
Membranipora, Vincularia, ete., auct.), (Fig. 474). Zoaria encrusting or erect. Oral 
| 
Cumulipora angulata, Miinst. Oligocene; Doberg, near Biinde. A, Zoarium, natural size. B, Upper surface, 
enlarged. C, Vertical section, enlarged (after Reuss). 
A B C 

Fic. 476. 
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., VOrb.) Differs from Onychocella in having 
a larger aperture, which is often somewhat expanded below, and having vibracular 
cells instead of avicularia. Cretaceous and Tertiary. 
?Cumulipora, Miinst. (Fig. 476).  Zoaria irregularly massive. Zoccia partly 
recumbent, partly erect, and placed one above the other, so that they appear to form 
tabulated tubes. Tertiary. 
