1886. ] POSITION AND CLASSIFICATION OF SPONGES. 573 
we have Ceraospongiz before us. Transitional forms between the 
Cornacuspongie with supporting spicules cemented by spongin, and 
Cornacuspongiz without spicules in their fibres (horny sponges), 
are not unfrequent. 
One whole subfamily, the Chalininee, comprising nearly 300 species, 
is composed of such transitional forms. The supporting spicules met 
with in the Cornacuspongiz are invariably monaxon without a 
swelling at one end. Besides these more or less rod-shaped sup- 
porting spicules, we also find in some of the Sponges belonging 
to this group so-called flesh-spicules—small, irregular curved or 
complicated elements scattered throughout the Mesoglcea. These 
occur associated with spicules in the fibrous supporting skeleton 
and also in those forms which have no spicules in their horny 
supporting skeleton. To this group also the genera Halisarca and 
Bayalus belong, which have no skeleton at all, and appear as 
askeletous forms of the Aplysillide type. The term Cornacuspongize 
was established by Vosmaer (1550), and used by him in a very similar 
sense to that in which it is used here. The group Chondrospongie, 
on the other hand, is in the sense given above a new one; it nearly 
coincides with Vosmaer’s group Spiculispongiz (1550). In a former 
paper (889) I had retained the group Myxospongiee, for the sake of 
convenience, preliminarily only, and agreeing at the time with Sollas 
(1440) that it was unnatural. The manner in which I have distri- 
buted the members of the Myxospongiz among other groups is in 
accordance with the view expressed by F. E. Schulze in a letter. 
We have accordingly to divide the subclass Silicea into three 
groups in the following manner :— 
Subclassis SIZICHA, Lendenfeld. 
Mesoglcea soft ; support- Mesogleea hard ; tough- Mesoglcea soft ; support- 
ingskeleton oftenstrength- | nessachieved by the hard- | ing skeleton strengthened 
ened withsiliceouscement. | ening of the ground-sub- | by spongin cement; or 
Spicules triaxon. stance. Spicules tetraxon, | exclusively formed of 
monaxon, anaxon, or ab- spongin, with or without 
sent; generally corticate. | foreign bodies. Spicules 
monaxon, or absent. 
2. Ordo HEXACTI- 3. Ordo CHONDRO- 4, Ordo CORNACU- 
NELLIDA, SPONGLA, SPONGLE, 
O. Schmidt. Lendenfeld. V osmaer. 
Expressed in the usual manner, the class Spongize would be 
accordingly divided into four Orders in the following manner :— 
Classis SPONGIZ, auctorum. 
Ceelentera with branching canal-system, without movable appen- 
dages ; the organs of which are developed from cells of the mesoglea. 
With simple epithelia. 
I. Subclassis CALCAREA, Grant. 
Spongiz with a skeleton composed of spicules which consist 
chiefly of carbonate of lime. 
