CHAP. IV.] ST. THOMAS TO BERMUDAS. 257 
and the one in which the operculum was most marked. The 
whole group of Stylasteraceans requires careful revision, when 
very likely it may be found necessary to merge Cryptohelia 
and Endohelia in Stylaster. 
Two examples of the sponge-body of a very handsome //ya- 
lonema were sifted out of the coral-mud. Unfortunately, in 
both cases the sponge had been torn from the central coil, and 
the absence of the coil might have thrown some little doubt 
upon the form and mode of finish of the complete animal; so 
that it was extremely fortunate that a young specimen. of the 
same species, about 40 mm. in length, was caught in the tangles 
quite perfect. 
THyalonema toxeres, WyvitLE 'Tuomson, resembles closely the 
other known species, (7. Lusitanicum and H. Sieboldi, in gen- 
eral appearance and in the arrangement of its parts. A more 
or less funnel-shaped sponge presents two surfaces, covered 
with a net-work of different patterns formed by varying ar- 
rangements of large five-rayed spicules. The upper concave 
surface shows a number of oscular openings, irregularly ar- 
ranged; and the lower surface a more uniform net-work of 
pores, some of which seem to be inhalent and others exhal- 
ent. The central axis of this sponge is closely warped into 
the upper part of a coil of long and strong glassy spicules, 
which, as in the other species, serve to anchor the sponge in the 
soft mud. Both of the specimens dredged have the sponge 
more flattened and expanded than it is in /7. Lusttanicum. In 
one of them it is nearly flat (Fig. 66), forming a uniform cake- 
like expansion, 80 mm. in length by 70 mm. in width, and about 
8 mm. in thickness. The upper or oscular surface is covered 
by an exceedingly close net- work, with groups of large open- 
ings at nearly equal intervals. It is slightly raised in the cen- 
tre. The central elevation is followed by a slight depression, 
and the upper wall then passes out nearly horizontally to a 
sharp peripheral edge, fringed with long, delicate spicules, each 
