Sponge-spicule in the Spongida. 171 
there were present the spiro-sinuous flesh-spicules of Cliona 
abyssorum, which I had described and figured from a specimen 
found in Lophohelia prolifera, dredged up at the mouth of the 
English Channel (‘ Annals,’ 1874, vol. xiv. p. 249, pl. xiv. 
fig. 33, and pl. xv. fig. 45, a, 6, c), to such an extent that it 
appears in great plurality even in the minute fragments of 
both slides mounted by Dr. Millar, also in the dust of the 
pill-box containing the specimen of Rhaphidotheca, and in 
crevices of the pieces of Lophohelia which accompanied it. 
Thus a very different aspect of this little sponge became 
manifest, and I could not help inferring that the Esperia, as 
is often the case with sponges not content with their own spi- 
cules, or having no means of obtaining silex for forming a 
sufficient number of them, had not only appropriated the 
sinuous flesh-spicules of Cliona abyssorum, which infests 
Lophohelia prolifera, but the pin-like skeletal ones also; and 
and that, after all, the presence of the pin-like spicules with 
their heads outwards did not, in this instance, invalidate the 
view mentioned, viz. that the proper spicules of a sponge are 
never found in that sponge with their large ends outwards. 
Still, the pin-like spicule in this little sponge is not iden- 
tical in form with that of Cliona abyssorum, as may be seen 
by comparing Mr. Kent’s with my figures of it (/. c.); and the 
only conclusion I can come to, in consequence, is, that Mr. 
Kent’s will be found to characterize a variety of Cliona abys- 
sorum in the Lophohelia prolifera, bearing the pin-like spicule 
of this misleading little sponge, or the latter has been modi- 
fied in form by the Esperia itself ; which, it is very desirable to 
determine. 
When viewed in a perpendicular section laterally, the real 
surface of the Esperia can be seen to be marked, as usual, by 
the horizontal layer of acerates binding together the points of 
the sub-pinlike skeleton-spicules of the Esperia, in which 
none of the sub-pinlike or large ends are observed to be out- 
wards, while the reverse is the case with all the pin-like spi- 
cules that form its crust, which have been inferred to have 
come from a Cliona—the former being the case with the 
“proper spicules” of a sponge, and the latter that of spicules 
derived from another or foreign source. It would be desirable, 
then, to ascertain if the Cliona, which in all probability infests 
the Lophohelia on which this little sponge has grown, has a 
pin-like spicule like that covering the Hsperia. 
If, however, Mr. Kent has not been happy in the instance 
of Rhaphidotheca Marshall-Hallii, as opposed to my views, he 
has caused me to considerably modify them, as well as the 
statement made in my “ Notes introductory to the Study of 
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