15 
44 show, which are drawn with the camera lucida at the same 
power (Zeiss A). 
6°. M. ta. d. bif. (fureated patento-ternate). The shaft and the 
teeth are yet thinner than in the M. ta.® = 90°, but thicker than 
in the M. ta. ®< 90°. The relation between d and d! can be: 
d>d', d=d! or d<d!. They are not extremely frequent but 
not at all rare. 
7°. gl. The globulates are of the ordinary shape. 
8°. st. The stellate spieules; have about the same shape as those 
of I. pallida but are not thorned. A few times I have seen spe- 
cimens with some superficially thorned radii, only visible at a 
great power. (Fig. 47, Pl. II). 
9°, glst. The sphero-stellate spicules are much larger than those of 
I. pallida. The radii are very small; see Fig. 48 on Plate II. 
In examining this Sponge with the loupe, you will observe many 
oscula, one time placed on an elevation, another time the wall is 
unconspicuous. Between these oscula there are to be seen much 
smaller pores which have about the same diameter as the globu- 
late spicules. The average size of the oscula is about five times 
the diameter of the pores. Sections through these pores and os- 
cula teach us that both are differing only in size. Very often 
it is diffieult to say if you see an osculum or a pore. On this 
character Sollas has founded his genus /sops, and I believe he 
is quite right. Sollas disapproves Oscar Schmidt’s methode in erec- 
ting the genus Pyxites for specimens of geodine Sponges which 
have the oscula congregated in groups. And again Sollas is right 
in doing so. Lamarck’s diagnosis of his Geodia is clear enough. 
According to the law of priority, Lamarck’s Geodia gibberosa 
must still be named so, and not Pyxites. Schmidt’s Pyxites has 
no „raison d’etre”. Thus I accept Sollas Isops. On Plate IV 
fig. 116 I have given an illustration of a section of Isops sphae- 
roides n. sp. The aspect of the outer surface is hardly differing 
from that of Isops pallid«, illustrated on plate IV, fig. 117. It must 
be remarked that there are also to be seen little conical elevations, 
of different size. I seems to me that these are the places where 
