570 DR. R. VON LENDENFELD ON THE sysTEMATIC [Dec. 21, 
IV. Tue CLASSIFICATION OF SPONGES. 
Having thus ascertained the systematic position of the Sponges as 
a group, we now approach the second part of our work. 
Every one will agree that no satisfactory classificatory system of 
Sponges exists at present. Spongologists are in the habit of approach- 
ing this subject with great caution, I may say with diffidence. 
It is a remarkable fact that the leading spongologist of the day, 
my esteemed teacher Prof. F. E. Schulze, in Berlin, has not attempted 
to work out a classificatory system of Sponges, whilst others have 
made some desultory efforts in that direction. It is self-evident 
that the systems established by Bowerbank, O. Schmidt, Gray, and 
others, which date from a time when virtually nothing was known 
. about Sponges, have now become obsolete. The most successful 
attempt at establishing a system of Sponges is doubtless that of 
Vosmaer (1550), who, however, approaches his task with great 
diffidence ; everywhere we meet in his work with ‘ preliminary ” 
classifications. Some geologists, principally Zittel (1635) and Sollas 
(1455), have classified the Sponges in a rather high-handed manner, 
establishing subclasses, orders, &c., without regard to details like 
families and genera. Zittel particularly attached too much importance 
to the fossil Sponges. 
In the groups themselves more satisfactory detail work has recently 
been done. F. E. Schulze (1369) has worked out the Hexactinellids 
of the ‘ Challenger’ with results which are as valuable and useful 
as the material at his disposal was abundant and interesting. Zittel 
(1626-1629) has in a satisfactory manner dealt witb the fossil 
Sponges belonging to the same group. The Lithistids and Tetractinel- 
lids, both fossil and recent, have been carefully investigated by Zittel 
(1639) and Sollas (1453). 1 (888) have, with the aid of the works 
of Hackel (627-629) and Poléjaeff (1179) at my disposal, established 
a system of Calcareous Sponges based on my investigations of the 
rich Australian Sponge-fauna, which appears fairly satisfactory. 
The Monactinellids have been carefully studied by Vosmaer (1545), 
Ridley (1261), and Ridley and Dendy (1265-1266), and I have 
myself devoted much labour to their investigation, and have made 
(870) an attempt at classifying them, which, however, was unsuc- 
cessful. The Australian Fauna is exceedingly rich in Monactinellids, 
and my collection, of over 300 species, has enabled me to work 
out the classification of some of the groups in detail. 
No attempt has hitherto been made to classify the Horny Sponges 
excepting one, contained in a short paper of Vosmaer (1552), 
establishing five groups, in accordance with the views previously 
expressed by myself (868), and based on the result of the researches 
into the structure of horny sponges by F. E. Schulze (1345, 1348, 
1349, 1351) and myself (868). The Australian marine fauna is ex- 
ceedingly rich in horny sponges, so that I have been enabled to 
work out their relationsbips in detail. 
If we review the Sponges as a whole, we shall be struck with 
the great fundamental difference between the Calcareous and all 
