074 DR. R. VON LENDENFELD ON THE SYSTEMATIC [Dee. 21, 
1. Ordo CALCISPONGIA, Blainville. 
The oaly Order, with the characters of the Subclassis. 
II. Subclassis S7ZJCEA, Lendenfeld. 
Spongiz with a skeleton composed of siliceous spicules and their 
descendants with horny aspiculous skeleton and askeletous forms. 
2. Ordo HEXACTINELLIDA, O. Schmidt. 
Silicea with soft mesogloea. Supporting skeleton often strengthened 
with siliceous cement. Spicules triaxon. 
3. Ordo CHONDROSPONGIA, Lendenfeld. 
Silicea in which the toughness is achieved by the mesoglea or 
mesodermal ground-substance becoming cartilaginous, whilst the 
spicules remain isolated. Spicules tetraxon, monaxon (tylostylus), 
or absent ; generally corticate. 
4. Ordo CORNACUSPONGIA, Vosmaer. 
Silicea with soft mesoglcea or mesodermal ground-substance; the 
supporting skeleton, composed of bundles of monaxonid not tylostyle 
spicules, is strengthened by spongin, which cements the spicules. 
These may disappear altogether, and the skeleton is then composed of 
spongin with or without foreign bodies. The skeleton rarely dis- 
appears altogether. 
Having thus divided the Class Spongize into four Orders, we may 
preceed to the further division of the Orders into Families. 
I. Ordo CALCISPONGIA, Blainville. 
This Order has been divided by Hickel (627-629) into the well- 
known three families Ascones, Leucones, and Sycones, with seven 
genera in each. Poléjaeff (1179) has divided the group into two 
Suborders and replaced Hickel’s genera by the older and wider 
genera of Grant and others. I (888) have tried to combine Hiickel’s 
and Poléjaeff’s classifications, and have added three new families to 
the existing ones. 
I have retained Poléjaeff’s terms for the two Suborders, but have 
altered their meaning. In some Calcareous Sponges the whole of 
the entoderm consists of collar-cells. There are no entodermal 
pavement-cells in these forms. These constitute my first Suborder 
Homoceela. In others the collar-cells are found in the ciliated 
chambers only, while the central gastral cavity is clothed with 
entodermal pavement-cells. I combine these forms in the Suborder 
Heteroceela. 
To the Homoceela belong besides Hiackel’s Asconidz, my families 
Homodermide and Leucopside. I acknowledge Hickel’s seven 
genera of the Asconide. 
In the Heteroceela, Hickel’s families Leuconide and Syconidz 
seep with Carter’s Teichonidee and my family Sylleibide are 
placed. 
