1913-14.] Siliceous Sponge of the Order Hexactinellida. 
23 
III. — Note on a Siliceous Sponge of the Order Hexactinellida from 
South Shetland. By Principal Sir William Turner, K.C.B., 
D.C.L., F.K.S. 
(Read December 1, 1913. MS. received December 2, 1913.) 
The specimen was presented to me by Mr G. Millen Coughtrey, who 
obtained it in Admiralty Bay, South Shetland, lat. 62° S., and long. 58° W., 
in 1912. It was procured in about 20 fathoms, and was brought to the 
surface when the ship’s anchor was weighed. It consisted of white, delicate, 
thread-like spicules collected into two tufts or bundles. At the first glance 
the threads might easily have been mistaken for white hair, but they 
would not burn ; neither were they calcareous, for they were not acted on 
by mineral acids. From their vitreous appearance they were obviously 
siliceous and indeed were not unlike spunglass. Their aspect and com- 
position led me to regard them as belonging to a siliceous sponge, but the 
body of the sponge was wanting. In its absence one had to rely on the 
characters of the tufts and spicules in attempting to determine the genus 
of the sponge. 
One tuft was about 40 cm. (16 inches) long, and 3J cm. at its greatest 
transverse diameter. The thread-like spicules were compacted and inter- 
laced together at the proximal and mid parts of the tuft, but at the distal 
end it was somewhat dishevelled. It contained many hundred spicules 
and seemed as if it had belonged to one sponge. The smaller tuft was not 
so compact and might possibly have been divided into two parts, one for 
each of two smaller sponges. 
The threads were the basalia or basal spicules of the sponge, which 
had grown downwards from the base of its body and had penetrated the 
mud on the floor of the sea in which the sponge lived. In weighing the 
ship’s anchor the tufts of basal spicules had been drawn up at the same 
time. The spicules were so brittle that it was difficult to pick a single 
one out of the tuft without breaking it, but with care I obtained examples 
30 cm. (12 inches) long. The spicules were smooth on the surface, 
translucent, and the transverse diameter ranged from 35 to 92 jm. In 
many of the smaller sizes the appearance of a narrow canal in the long 
axis of the spicule was seen, but in the wider spicules no structural 
differentiation was observed. One end of the spicule was frequently 
