PORIFERA [SPONGES]. 29 
with a serrated spiral ridge with the teeth pointing upwards High Case 
( Fl £- 8 )* . TablYcase 
The body of the sponge forms a thick-walled cup, which, how- 2 a, b. 
ever, is so loosely constructed that light can be seen through it. The 
interior is divided up by four to eight vertical partitions radiating 
from a central spike. The top of the cup is closed by a thin sieve- 
plate with perforated 44 quarters ” corresponding to the divisions 
inside. A 44 commensal ” zoophyte ( Palythoa ) is always found 
investing the upper end of the glass rope, and occasionally it forms 
pits (often mistaken for oscules) on the surface of the sponge itself. 
Unfortunately the Palythoa has become detached from the upper 
part of the root- tuft of the specimen figured, but is abundant on the 
surface of the sponge body. The Japanese deep-sea shark-fishers 
obtain the sponge by means of hooks attached to their deep-sea lines. 
By a curious parallel, the deep-sea shark-fishers of Portugal obtain a 
nearly allied species of Hyalonema in somewhat the same manner. 
Lophocalyx philippi nensis , from Cebu (in fluid, Table Case 2a), 
which forms a small compact thick-walled cup with long root-tufts, 
furnishes a beautiful example of bud formation, buds of all ages 
being present on the specimens. 
Sub-Order II. Dictyonina. In this group the skeleton, even in 
the earliest stages, forms a rigid framework constructed of the fused 
rays of large regular six-rayed spicules. These sponges usually have 
a vitreous, finely honeycombed appearance. The magnificent 
Aphrocallistes vastus (Fig. 1), in the centre of Case III., is shaped 
like a vase with a thick stem, and with large folds projecting out 
from the walls. The very fine specimen of Chonelasma calyx , to the 
right of the former, is bowl-shaped, and with finger-like pockets 
often extending down, like the 44 roots ” of a Banyan tree, till they 
reach the base on which the sponge is growing. The fossil Ventri- 
culites common in flints from the Chalk are Dictyonine Sponges.* 
CLASS HI— DEMOSPONGL® OB COMMON SPONGES. 
The Common Sponges include all sponges other than the 
Calcareous and Glass Sponges. 
Tetractinellida (Four-Bay Sponges). 
The sponges of this Order are often spherical with a radiating High Case IV. 
structure ( Graniella , IV. 3), or they may form tough leathery cakes 5 1S ^- 
Jrartition, 
* A later classification of Hexactinellida by Prof. F. E. Schulze is into 
two sub- orders: (1) Hexasterophora (including Dictyonina) with hexaster flesh 
spicules, and (2) Amphidiscophora with Amphidisks. See Upright Table 
Case A, columns 6 and 7. 
