From the North Sea. 85 
they consist of spindle-shaped needles, of exactly the same 
type as those of the stem, but smaller. Ten measurements have 
given from 1°14 millim. in length and 0:013 millim. in thick- 
ness to 0°4 millim. in length and 0°011 millim. in thickness ; 
the mean length was 0°73 millim., and the relation of length 
to thickness in one as 100 : 2°86, in another as 100: 1-09, the 
mean of twelve measurements being 100: 1°85. Very rarely 
there appear some few small straight needles without nodules 
near the middle (fig. 27). The nearer the surface, the more 
the bundles divide; but, regularly, not one of their spicules 
reaches out of the dermal layer, in which appear other 
spicules (fig. 34) of the same type as those in the skin of the 
stem, but longer, arcuated, without nodule (fig. 35), and 
placed in the same manner. The measurements gave from 
0°45 millim. in length and 0-004 millim. in thickness to 0°34 
millim. in length and 0:0046 millim. in thickness; the mean 
length was 0°39 millim. ; the relation of length to thickness 
in one as 100: 1°25, in another as 100: 0:8, the mean being 
100 : 1. 
The interstices between these bundles of spicules, which 
form the partitions of the canal-system of the head, are filled 
with the parenchyma, which, although it has been a very long 
time under the influence of the alcohol, has a yellowish-brown 
colour, is firm and tough, has very numerous, mostly oblong 
corpuscles and granules, among which there are some larger 
ones with granular contents (fig. 36). 
From the rather thickened base of the stem, out of its 
dermal layer, a great number of roots go off, irregular and 
branched filaments here and there forming loops and gradually 
spreading over a surface almost twice as great as the upper 
surface of the head (fig. 37). The roots consist in greater 
part of a tolerably transparent colourless substance, the same 
as that of the skin, covered by a somewhat thin layer of fine, 
yellowish, granular matter. Very rare, extremely small and 
straight spicules may possibly belong to this layer, though it 
is very difficult to refer them to it with certainty among the 
great number of foreign objects of many kinds which are 
attached by the granular layer’s having crept over them and 
penetrated even into the canal of the fragments of sponge- 
spicules (fig. 38). 
When the stem of the sponge is broken not far from the 
root, and the upper part, thus separated from the basal, is 
turned upside down and placed on the flattened surface of the 
head, the stump of the stem directed upwards, it has an un- 
uestionable likeness to the well-known Hyalonema Steboldi, 
ivay, as this has been hitherto exhibited. What we have 
