384 Remarks by My. H. J. Carter. 
other on the mitre-shaped inflation of the head, and not four 
above and four below, as delineated by Mr. Higgin (Pl. XXI. 
fig. 10) from the specimen of [Hyalonema Steboldii in the 
Liverpool Free Museum. This shows that, besides four arms 
recurved and opposite on a mitre-shaped inflation being the 
principle on which the head of the anchoring-spicule is formed 
generally in the Hyalonemata, it is subject to the modifications 
mentioned in all these specimens. 
As regards the bearing of this “ principle of formation” 
on the termination of the anchoring-spicules of the genus 
ftossella, in which there are also four opposite arms, it will 
be seen by comparing the two that there is no “ inflation ”’ 
in Rossella, but the arms come off from the end of the spicule 
directly ; also that the diameter of the head, taken in its en- 
tirety, is far greater than that of any part of the shaft—which 
is the opposite in Hyalonema, in which the so-called “ arms ”’ 
are little more than spines, while in Rossel/a, from their size 
and length, they are really “arms;”’ lastly, that the shafts of 
the anchoring-spicules in the genus Rossella are not spined, 
but smooth. 
The large “ birotulate, no. 11,” p. 380, appears to be the full- 
grown size of the minute or embryonal one “ no. 13,” as evi- 
denced by gradationary development in a fragment of Hyalo- 
nema Steboldii mounted in Canada balsam; while the dif- 
ferences in form do not amount to more than modifications of 
the normal type—consisting of a shaft, and eight arms opposite 
and recurved, all round each end; which arms being knife- 
shaped with their thin edges respectively extended into a 
faleate form towards the shaft, with which they are thus 
united, constitutes this flesh-spicule the representative among 
the Hexactinellid sponges of the common equianchorate. 
The “spinicruces” of Brandt, so well figured by Dr. 
Bowerbank (Brit. Spong. vol. i. pl. vi. figs. 153-157, p. 252), 
have their representatives, as stated by Mr. Higgin (p. 381), 
in the crucial spicules with spined extremities, so abundant 
just where the sponge-head joins the cord in Hyalonema 
cebuense (Pl. XXII. fig. 2). 
They are similarly situated in HZ. Steboldit and in H. lusi- 
tanicum ; but we do not find that they extend upwards further 
than this. 
In some very small specimens of HZ. lusttanicum dredged 
up off the Butt of the Lewis on board H.M.S. ‘ Porcupine’ 
both with and without the Polype, these spicules are equally 
abundant at the poimt mentioned; while the cord in HZ. lusi- 
tanicum, not stopping halfway up the sponge-head as in 
H. Steboldii, but passing entirely through the head so as to 
