BE Mr. R. Hope on two new 
the spicules in one particular, namely, that in the latter the 
turn of the spiral is usually more or less compressed laterally ; 
that is, the imitation would be closer, if we suppose the pencil 
to have an elliptical instead of a circular section and the wire 
to be laid along one of the thinner ends of the ellipse at right 
angles to the long diameter. 
The central twist of these toxa is admirably shown in a 
photograph from one of my preparations of the sponge, for 
which I am indebted to the kindness and skill of my friend 
Mr. J. Howard Mummery, F.R.M.S., and of which the 
figure A, 8 is a copy. 
The smaller toxa (fig. A, 7) do not show this central twist, 
but neither do they lie in one plane, one turn of a very slack 
spiral apparently being completed in the whole length, or 
nearly so, of the spicule. 
The only other sponge which, so far as I know, possesses 
this (that is, the long-armed) form of toxite is Amphilectus 
foliatus (Vosmaer), Bowk. (= Halichondria Joliata, Bowk., 
Mon. Brit. Spong. iii. p. 198, pl. Ixxiii. figs. 1-5, and iv. 
p- 106; and Carter, Ann. & Mag. Nat. Hist. (4) 1876, xvi. 
p- 310, pl. xiii. fig. 10, and pl. xv. figs. 29a, 6). Hal- 
chondria mutulus, Bowk. (Mon. Brit. Spong. 11. p. 209, 
pl. Ixxiv. figs. 4-8, and iv. p. 96), in which this toxite is 
also found, has the same spiculation as A. foliatus; and 
examination of the type preparations (there is no type spec?- 
men of H, mutulus) in the British Museum leads me to con- 
clude that, if not the same sponge, which I think they are, 
the two forms must be considered merely as varieties of the 
same species. 
Through the kindness of Mr. Carter in lending me his 
preparation of A. foliatus from the N.W. coast of Shetland 
(op. et loc. cit.) I have been enabled to examine its spicula- 
tion and compare it deliberately with that of M. strepsitoxa. 
The toxites of the former are a little longer on the average and 
convey an impression of more luxuriant growth—that is, they 
are frequently flexuous, and the central twist is often sharper 
and not seldom even reversed, so as to form a loop, as 
described by Dr. Bowerbank (op. cect. iii. pp. 200 and 211) 
and figured by Mr. Carter (/. ¢. pl. xii. fig. 106) ; the spiral 
also is often more compressed laterally, and in some few cases 
it is doubtful if it is present at all. With these slight modifi- 
cations the spicule is ddentical in the two species. 
In his description of Halichondria foliata (Ann. & Mag. 
Nat. Hist. /. c.) Mr. Carter mentions that the tricurvate of 
that sponge was also found in Microciona armata, as he knew 
from a specimen taken at Budleigh Salterton ; it is clear that 
