8 Rev. T. Hincks’s Contributions towards 
trated to some depth by a multitude of the slender rootlets. 
Whether the species is ever found on hard bodies, attached in 
the usual way, Ido not know. All the specimens which I 
have examined are furnished with the radical appendages ; 
and taking into account the convexity of the dorsal surface, I 
should have been inclined to suppose that this is the normal 
condition, and that in M. radicifera and Cribrilina ferox we 
have forms specially modified for life on soft or porous sub- 
stances. But as MacGillivray states that the species is found 
incrusting Algez, the question whether the radical appendages 
are provisional or permanent structures can only be settled 
after further investigation*. 
Cribrilina tubulifera, n. sp. 
(PL. I. fig. 7.) 
Zoecia oval, white, the front occupied by a flattened area 
of about the width of the orifice, which is surrounded (except 
above) by a row of erect tubular processes (about fourteen) 
open at the top; the inclosed space crossed by shallow de- 
pressions or furrows, in each of which are situated four rather 
large pores; numerous minute slightly raised foramina irre- 
gularly distributed ; outside the line of tubules the cell-wall, 
which descends abruptly, is broken up into a number of 
lobate processes separated by narrow elongate spaces ; orifice 
arched above, lower margin straight, peristome not raised, 
three spines above, two of which are usually very slightly 
divided at the top. Occtwm (?). 
Two small colonies occur on shell. 
Cribrilina speciosa, n. sp. 
(Pl. I. fig. 8.) 
Zoartum of a brownish colour. Zowcra large, usually elon- 
gate-ovate (sometimes shorter), quincuncial, distinct, not very 
convex, carinate, a large proportion of the front occupied by 
an oval areatraversed down the centre by a prominent keel, from 
which ridges (7-12) pass to the border, the furrows between 
them not punctured; area surrounded by a narrow margin 
of smooth cell-wall; orifice suborbicular, rather contracted 
below ; no spines or avicularia. Owciwm large and rounded, 
smooth, dense, whitish, slightly flattened im front, and above 
the flat space rising into a knob, from which a shallow sig- 
moid fissure descends on each side. 
* [ have a specimen spreading over a tough fibrous substance (? stem 
of weed) into which the radical fibres (which are present in great abun- 
dance) have penetrated, binding the polyzoon closely and firmly to the 
surface. 
