420 
Bibliographical Notice . 
invested by a coating of spongin ; but this view is given np as 
untenable, and, with Schulze, he now confesses himself unable to 
satisfactorily explain their origin ; but it seems certain that, though 
not produced by the sponge, these filaments are in some way neces- 
sary to its existence, and may thus be compared with the zooxan- 
thellae or yellow cells frequently found in low forms of marine life. 
Curiously enough these filaments are, in the author’s opinion, inva- 
riably associated with this genus of sponges and with no other, and 
they are as abundant in the Australian as in the Mediterranean 
species. 
The sponges included in the Spongelidoe, or third main group of 
the Monoceratina, have a reticulate or dendritic skeleton of. solid 
horny fibres without proper spicules, but containing foreign bodies 
and occasionally entirely replaced by large sand-grains ; sometimes 
rod- or S-shaped flesh-spicules are present. The ground-substance 
or mesoderm is transparent, and the ciliated chambers are large and 
sac-shaped and do not possess special efferent canals. This group 
is more nearly allied to the siliceous Heterorhaphidae of Eidley and 
Bendy, and includes only five genera, two of which, Sigmatella and 
Haastici , are new ; the latter is somewhat remarkable in having a 
layer of minute oval siliceous bodies sheathing the fibre. The 
generic term Spongelia, Nardo, is preferred by the author to that of 
JDysidea, Johnston, on the ground of priority, and our English 
authors who regain Johnston’s name are blamed for their ignorance 
of Nardo’s works; but Dr. Lendenfeld does not seem to bo aware 
that Nardo’s term was unaccompanied by any description whatever, 
and is therefore invalid. As stated by Oscar Schmidt, the names 
given by Nardo must remain as shadows merely, since this author 
did not live to carry out his intention of describing the forms them- 
selves ; and though it pleased Oscar Schmidt to adopt some of them 
subsequently, Spongelia included, this would by no means be suffi- 
cient to displace the properly constituted term Bysidea proposed by 
Johnston before 0. Schmidt published anything respecting the 
bodiless term Spongelia. Dr. Lendenfeld has another reason for 
preferring Spongelia , equally as valid as its assumed priority, viz. 
“ because Schulze, who for the first time defined the genus in a 
really scientific manner, used that name.” 
In the remaining principal division of Lenden fold’s system, that 
of the order Hexaceratina, the sponges may have skeletons of pithed 
horny fibres, or of horny spicules, or they may be without skeletons 
at all. They are furnished with large sac shaped ciliated chambers, 
with simple canals. These sponges are regarded as forming a 
natural group, most closely allied to the siliceous Hexactinellida ; 
but, judging from the distinguishing features of the three families 
which constitute the group, it is difficult to perceive in what way 
they are related to each other or to the Hexactinellida. Thus in 
the leading family, the Darwinellida), there are fibres and horny 
spicules, the next family of the Aplysidae has fibres only in the 
skeleton, whilst in the third family of the Halisarcidse there are 
neither fibres nor spicules. 
Perhaps the most peculiar horny sponges are those included in 
