276 DR. J. S. BOWERBANK ON (Apr. 6, 
specimen. The confluent rotulate form of skeleton-structure is not 
confined to the siliceo-fibrous sponges ; it also occurs in the dermis 
of arare British sponge, Desmacidon rotalis. In this case it does 
not occur in the internal skeleton of the sponge, but in the reticulated 
dermis only. I have figured this beautiful dermal tissue in vol. iii. 
pl. xe. fig. 9, ‘Monograph of the British Spongiade.’ 
The specimen of Deanea virgultosa figured was presented to me by 
my late friend Mr. H. Deane, along with those of Farrea gassioti 
and pocillum; and I presume it is from the same locality as those 
species. 
FarREA FISTULATA, Bowerbank. 
Sponge fistulous, orifices both terminal and lateral, very large, 
parietes thin. Surfaces, exterior and interior, even, but rough to the 
touch, each abundantly armed with a single series of harrow-like 
teeth, based on the angles of the skeleton-tissues, and projected 
outwardly from their respective surfaces. Oscula and pores un- 
known. Dermal membrane thin, abundantly spiculous; tension- 
spicula acerate, variable in size, rather numerous ; retentive spicula 
simple and contort, bihamate, numerous, dispersed. Skeleton-fibre 
cylindrical, smooth and even; canals large and very distinct ; rete 
symmetrically quadrangular, areas usually square. Internal de- 
fensive spicula attenuato-acuate, basally spined, based on the skele- 
ton-fibres, projected at about right angles into the areas of the rete. 
Sarcode dark amber-colour, thinly coating the skeleton-structures. 
Colour, dried state, dark amber-brown. 
Hab. West-Indian seas ? 
Examined in the dried state. - 
This remarkable sponge consists of a single thin stratum of skele- 
ton-tissue in the form of a compound pipe about four lines in dia- 
meter. It has all the appearance of being only a portion of a more 
perfect specimen. It is but an inch in length, but in that short 
space it has six open terminations of what has apparently been as 
many ramifications of its fistulous structure; and none of these 
orifices have a natural or an even margin. The general surface of 
the specimen is even, and no indications are apparent of either oscula 
or pores. The dermal membrane is in an excellent state of preserva- 
tion on the surface of the sponge; and from its present condition it 
was evidently in a living state when taken. It is a thin translucent 
structure, abundantly spiculous. The tension-spicula are slender 
and acerate, not very numerous ; they are variable in size and irregu- 
larly disposed on the surface of the membrane. The bihamate 
retentive spicula are rather numerously dispersed on the membrane ; 
they are slender and very equable in size. The skeleton isa remark- 
ably beautiful structure. The fibre is perfectly smooth, very equable 
in its diameter, and it is arranged as nearly as possible in a regular 
quadrangular network. The central canals are moderately large 
and very distinct, and are as equable in their diameter and mode of 
distribution as the rete of the skeleton is. The thin stratum of 
