Knowledge of the Freshwater Sponges. 97 
Miillert,” of which I distinguished ‘ Forma A,” “ Forma B,” 
and ‘‘ var. astrodiscus.” From observations made recently 
from fresh materials on ‘‘ Forma B,” this must be recognized 
as a distinct ‘ good” species, for which I propose the name 
of Ephydatia amphizona. 
The other question relates to the external parenchymatous 
envelope of the gemmules. I had previously found this in 
most of the indigenous species—Luspongilla lacustris, E. jor- 
danensis, and Ephydatia fluviatilis. It remained still unde- 
cided whether corresponding envelopes were present on the 
gemmules in “ Hphydatia Miilleri” and Trochospongilla 
erinaceus. r 
Having been able during the last vacation to investigate 
the above-mentioned forms in the fresh state, I can now fur- 
nish satisfactory information upon this question also. 
I. Ephydatia amphizona (syn. H. Miillerit, Forma B) was 
obtained from the Juvorka brook near Sobeic (Ostromer), 
with the same characters that I have described in my mono- 
graph. Nevertheless the structure of the gemmules is quite 
different, and divergent from all allied forms. Fig. 2 shows 
anearly median longitudinal section through a gemmule. In 
this we see the following layers :— 
1. Externally, an outer layer of amphidisci (a), which pro- 
ject with their columns and distal terminal disks freely from 
the parenchymatous layer (6), while the proximal terminal 
disks are inserted into the upper parenchyma. 
2. A tolerably thick parenchymatous layer (6) contains in 
its base the other layer of amphidisci (c), which is closely 
applied to 
3. The brown chitinous membrane (d). 
4, The inner space of the gemmule contains the germinal 
corpuscles (e@). 
Consequently Eph. amphizona is especially distinguished 
by the double layer of amphidisci in the parenchymatous en- 
velope of the gemmules from Eph. Miillert, var. astrodiscus, 
which, as I have recently convinced myself, possesses only a 
single layer of amphidisci in a feeble parenchymatous layer. 
As this latter form is also characterized by the form and habit 
of the exclusively hispid skeleton-spicules, it may be indicated 
by Lieberkiihn’s original name, Ephydatia Miiller’*. 
Whether the form indicated in my monograph as “ Eph. 
Miillert, Forma A,” and as characterized by the peculiarly 
formed amphidisci, is to be regarded as a variety of the above- 
* [M. mirabilis, Retzer, presents ‘a oe armature of amphidisci,”’ 
according to Marshall, in a paper of which a translation will appear in 
our next number.—Ep. | 
