3 
Reiches”, and said!) ihat the great geographical distribution of 
Schmidt’s Pachychalina made him suppose that P. compressa and 
Vel. polymorpha var. arctica were identical, „und zwar umsomehr, 
als die Abbildung Miklucho-Maclay’s und die Beschreibung O. Schmidts - 
fast übereinstimmen”. I think Dybowski is quite right in doing so. 
As Schmidt did not give a detailed description of the structure, 
Dybowski tried to characterise it. 
The horny fibres of the Sponge, are, especially in the lower 
parts, very conspicuous and the shape of the stout acerate spieu- 
les are quite the same in our Sponge, as in Dybowski’s. I have 
represented the Sponge in natural size un Plate I, fig. 14 and the 
skeleton-elements on Plate Ill, fisg. 65 and 66. 
Miklucho-Maclay says 1. c. pag. 6 from his var. arctica: „Diese 
Varietät zeigt solehe Verwachsungen der Aeste, dass sie die Gestalt 
eines dicken Blattes annimmt. Die Eigenthümlichkeit dieser Form 
drückt sich dadurch aus, dass nur die eine (untere) Seite zahl- 
reiche, sehr grosse, meist in Reihen angeordnete Oscula besitzt, 
‘wahrend die andere (obere) Fläche keine oder nur spärliche Oscula 
zeigt’. 
In comparing this description with our P. caulifera I have no 
doubt that this Sponge and P. compressa are closely allied. ‘The 
former, however is distinguished from the latter by a less marked 
development of the fibre, by shorter and stronger spicula and by 
the differentiated shaft. Both species, on the other hand, have 
several characters in common. So the particular arrangement of 
the oscula, the compressed form, the elastic fibres and the acerate 
spicules. 
These spicules are about 14 times longer than broad, those of 
P. compressa are more than 25 times longer than thick. The shape 
is sub-fusiform and the ends of the spicules have a kind of teat- 
shape, as is to be seen in figg. 66 and 65 on Plate III. The 
network of the fibres in the pedicel is much stronger and more 
developed than in the upper part of the Sponge. Strong primary 
1) 1. c. pag. 44. 
