British Species of Sponges. 337 
the specimen there alluded to was that which was described 
and conjecturally referred to WM. armata by Mr. Carter in 
1874 (Ann. & Mag. Nat. Hist. (4) xiv. p. 457). This state- 
ment thus concurs with Mr. Carter’s figure (i. c. pl. xxi. 
fig. 27) in fixing the shape of the toxite, and, together with 
the practical coincidence of the spicular measurements, clearly 
identifies the sponge described in 1874 with Microciona strep- 
sitoxva. 
The occurrence of so marked and striking a spicular form 
in these two sponges cannot but arrest the attention. [ts 
connexion with other forms of toxa seems plain, and it is 
easy to imagine how it may pass into them; indeed the 
smaller form of toxite in M. strepsttora (which I have not 
observed in A. foliatus) appears to be an intermediate form 
between it and the spined toxa, which are of frequent occur- 
rence in sponges of similar spiculation; yet the long-armed 
form is sufficiently distinct to make it highly improbable that 
the two sponges which contain it should be otherwise than 
closely related to one another, more closely, perhaps, than is 
either to any other known sponge. At present these two 
sponges find themselves not only in different genera but in 
different subfamilies; the skeletal structure of A. foliatus, 
however, but for the absence in it of the spined echinating 
spicule, agrees most closely with that of some forms of Clathria 
(e. g. C. compressa, O. S., Sp. des A. M. Taf. vi. fig. 1), and 
no doubt A. foliatus would find its most natural place in that 
Ketyonine genus, the presence or absence of the echinating 
spined style being apparently in this case also, as it is stated 
by Messrs. Ridley and Dendy to be in the genus Myzilla 
(‘ Challenger’ Monaxonida, p. 129), of comparatively little 
importance. 
The intimate interconnexion which exists between the 
genera Clathria, Microciona, and Lhaphidophlus is obvious 
from the remarkable correspondence of their spiculation, inde- 
pendently of the points of resemblance in their skeletal struc- 
ture. It is perhaps a question of appreciation and convenience 
(cf. ‘Challenger’ Monaxonida, p. 151) whether their generic 
separation should be maintained ; to unite them, if permissible 
on other grounds, would be to get rid of some of the difficulties 
which beset this group of sponges, and the consolidated genus 
would form a nucleus, around which it may be that other 
sponges of not very different spiculation would be found to 
group themselves naturally. 
Returning to the peculiar toxite of I. strepsitoxa, I have 
to mention the interesting fact that Mr. Carter has quite lately 
found at Budleigh Salterton a piece of chert from the Upper 
