104 - 
nen, körnigen Protoplasma-mantel und einer grossen Flus- 
sigkeits-alveole“. 
In Archiv f. Naturg. Bd. I. 1898 PI. VIII fig 14 he gives 
а figure of а „Blasenzelle“. 
The Sponges from the Volga, which are all preserved in 
formalin, are in the form of small white crusts and patches on 
stems of water-plants. Gemmules are present five examples, 
and а very careful search reveal the existence of amphidisks 
in all. 
А few small inconspicuous os-cules are visible on some 
of the specimens. 
The skeleton is formed of vertical main fibres several 
spicules thick and of rnore or less horizontal secondary fibres 
only one or two spicules thick. The main fibres form slightly 
spreading tufts at the surface of the sponge. 
In all cases there are both finely spined and smooth spi¬ 
cules present, and also very slender young forms usually with 
а central swelling 
In specimens E. 1.2, E. 16, and E. 20 belonging to Form А 
Vejdov^ky the skeleton spicules are decidedly shorter and 
thicker than those of the new variety behningi, and the 
spines of the rough spicules of Form A, though sparse 
and small, are more evident than in the latter. 
Indeed, in the new variety at first sight spicules all appear 
to be smooth, and spinous ones are only to be found with 
difficuity. 
The amphidisks in F о r m А have thicker and shorter 
shafts than in var behningi. I found а few blasenzellen in 
the specimens placed in Form A, but did not see them in 
var. behningi. Probably they are present in considerable 
numbers, but formalin does not act well as а preservative of 
histological structure in sponges. 
Prof. Weltner, very kindly sent me at my request, speci¬ 
mens ofEphydatia mülleri including one from the Spree 
at Berlin—the locality whence Lieberkühn’s original specimens 
came. Accordingly Jam able to give figures of the skeleton 
spicules and amphidisks of the Volga examples and of that 
from the Spree. The details of measurements are tabulated 
below: 
