all these spicules appear to have been smooth but there occur 
fragmentary spicules (Plate V, fig. 27) consisting of a straight 
neatly cylindrical shaft from the surface of which numerous 
minute recurved spines project, which probably are the shatts 
of anchoring spicules. Both the anchoring spicules and the 
spinous shafts are very rare. 
The resemblance of these anchoring spicules to those of 
existing sponges of the sub-order Lyssakina is sufficient to 
prove that they belonged to this group, and not improbably 
to the same sponges as the free hexactinellid spicules already 
described. A comparison may be made with the figures of 
several kinds of anchoring spicules of existing sponges given 
ye Vir, Carter (An. yMape Nat! Hist s. 44 Vol: 12) Pi XIV) 
also with those of MRossella antarctica, Carter (An. Mag. 
Nat. Hist. 5S. 4. Vol. 9, Pl. XXI). Similar shaped but larger 
anchoring spicules also occur in Hyalostelia (Hyalonema) 
Smithiz Young and Young (An. Mag. Nat. Hist. S. 4, Vol. XX, 
Pl. XIV) and more recently Mr. Carter has found them fossil 
in ‘carboniferous strata near Sligo in Ireland (An. Mag. Nat. 
Plists S557 Vobsopp. 210, ‘Ply X1V5: fie: io) “Mr. AWreht. has 
also figured a small four armed anchoring spicule with  spi- 
nous shaft from the Irish Chalk (op. cit, Pl. II, fig. 23 a, b). 
Spicules with Borings. 
(Plate Vi, figs: 28, 29). 
Out of several hundreds of sponge spicules from  Hor- 
stead which I have examined under the microscope, there are 
a few which give distinct evidence of having been perforated 
by some organism. The perforations are of the form of 
simple, unbranched, elongated, cylindrical tubes extending for 
various lengths in the interior of the shafts of acerate and 
trifid spicules. The tubes are sometimes curved and smooth, 
but occasionally they are convoluted and twisted. They ter- 
minate blindly in the interior of. the spicule. In some 
