122 Rev. T. Hincks’s Contributions towards 
friend reaches the axial canal; but some of them terminate in 
globular excavations. 
It is evident that the assimilation of the organic substance 
in the sponge-spicule by the vegetable organism produces the 
destruction of the siliceous structure; and probably the colloid 
silica unites with the protoplasm of the destroyer and forms 
an organic compound with it. 
Large cells and small nucleus-like cells operate, producing 
penetrations of corresponding diameters through the spicula 
down to the axial canal. The vegetable growth occurs there ; 
and the amount of erosion does not appear to be in relation 
with the size of the primary penetration. 
The organism is not an Achlya; and all that can be said is 
that it consists of cell-like bodies without very definite cell- 
walls, but evidently with a very delicately limiting texture 
surrounding a granular greenish plasma, and that there 
is much free and non-cellular plasma with bodies like small 
nuclei, the whole having a faint green tint. J have named 
this very lowly organic substance (which is probably a plant) 
Spongiophagus Cartert. 
XV.— Contributions towards a General History of the Marine 
Polyzoa. By the Rev. THomas Hines, B.A., F.R.S. 
[Plates I.-V. ] 
_ [Continued from p. 14.] 
Family Escharide (part.), Smitt. 
LEPRALIA, Johnston (part.). 
Lepralia clecdostoma, Smitt, var. orbicularis. 
This form differs from Smitt’s species in having a rather 
large circular avicularium, placed on an elevation at one side 
of the orifice and looking towards it, instead of a pointed 
avicularium. ‘The ocecium of L. cleidostoma is described as 
striated ; that of the present variety is usually smooth and 
silvery ; but I have met with one which was distinctly marked 
by radiating lines or slight ribs. On the whole I can see no 
sufficient reason for separating the two forms. 
Loc. Bass’s Straits, abundant in the dredgings. [Florida 
(Pourtales). | 
Lepralia Poissonii, Audouin. (?=Escharella setigera, Smitt.) 
This species was figured by Savigny in his work on Egypt, 
