76 M.C. Mereschkowsky on a new Genus of Sponge. 
WAGNERELLA, gen. nov. 
Sponges furnished with simple, long, calcareous spicules. 
Their body consists of a head or upper part, which is more or 
less globular, and of a long and slender peduncle which sup- 
ports the former part, and at the opposite extremity is fur- 
nished with an enlargement of conical form, by means of which 
it adheres to foreign objects. Habit resembling that of the 
Physemaria (fHaliphysema). 
I give this sponge its generic name in honour of Professor 
Nicolas Wagner of St. Petersburg. 
Wagnerella borealis, sp. nov. 
Head regularly rounded into the form of a ball, placed on a 
very long and slender peduncle, the whole never exceeding 
1 millim. in length (often 0°5 millim.). The cone of the 
peduncle as broad as high; the peduncle of uniform thickness 
throughout its whole length (sometimes a little wider above), 
nearly five times as long as the diameter of the head. All 
these parts (head, peduncle, and cone) have an interior cavity 
communicating freely throughout. ‘The walls of the body are 
composed of a fine organic membrane, with spicules. The 
spicules are of two kinds: some long and excessively fine, 
tapering towards the two ends, adorning the head, in the sur- 
face of which they are implanted in a radiating fashion only 
by one end; the others shorter and stouter, fusiform, placed 
both in the head and the peduncle, entirely implanted in the 
organic layer without projecting from it at all, and all, without 
exception, arranged horizontally in the foot. No grains of 
sand or any other foreign objects adhering to the surface of 
the sponge. Length (average) of the long spicules 0°035 
millim., of the shorter ones 0°01 millim. 
Locality. White Sea, neighbourhood of the islands of Solo- 
wetzky, near the monastery (at a depth of 2 fathoms) and near 
Kem (at a depth of 7 fathoms). 
Lastly, with regard to the two doubtful Physemaria, namely 
Haliphysema echinoides and Gastrophysema scopula, C., my 
opinion is as follows :— 
Haliphysema echinoides—When this is compared with 
Wyvillethomsonia Wallichii, Wright *, we see that we have 
to do with one organism, or, at any rate, with two varieties of 
a single organism, which, indeed, is admitted by M. Hickel 
himself. But if this be the case, it is perfectly evident that 
* Quart. Journ. Microsc. Sc. 1870, vol. x. pl. ii. 
