486 Miscellaneous. 
continuation of Mr. Macoun’s list will be looked forward to with 
interest. The apparent occurrence of natural hybrids of Wuphar (a 
characteristic, as appears from Mr. Thomas Meehan’s publications, 
of the allied genus Sarracenia) is one among many points of interest 
in the work, and the flora with which it deals is characterized by 
possessing 37 species of Astragalus, 2 of Potentilla, 27 of Ranun- 
culus, 26 of Sawifraga, 22 of Viola, 17 of Ribes, 16 of Arenaria, 14 
of Lupinus and of Anemone, 13 of Stellaria, 12 of Cornus, 10 each 
of Geum, Gnothera, Desmodium, and Claytonia, 8 of Acer, 7 of Rhus, 
and 5 of Paurnassia. Such a catalogue makes a botanist hope that 
it may be speedily followed by such a descriptive flora as shall be a 
credit to the largest of our colonies. 
G. 8S. Bovterr. 
MISCELLANEOUS. 
Freshwater Sponges as Improbable Causes of the Pollution of 
Tiver-water. 
Mr. Porrs reported that on the 9th of February he had visited 
and partially examined the forebay at Fairmount Waterworks, on 
the Schuylkill River, from which the water had been temporarily 
withdrawn, with a view to discover the winter condition of the 
freshwater sponges and the other inhabitants of that locality. He 
found by far the larger part of the wall-surface below the water-line 
inaccessible on account of a thick deposit of mud upon the bottom 
and much water remaining in the forebay. Wherever reached, 
however, and so far as the eye could detect in other places, 1t was 
covered by a mud-coloured incrustation of considerable thickness, 
which a more minute examination showed to be composed almost 
wholly of the statoblasts and spicules of the sponge Meyenia Leidyt. 
Some few fragments of Meyenia fluviatilis and Spongilla fragilis 
were seen, but the first-named was clearly the prevailing species. 
A sluiceway which formerly supplied the last of the old “ breast 
wheels” used in pumping into the reservoir, but from which the 
water had been for many months excluded, was entered and ex- 
amined. Here the remaining incrustation (much having doubtless 
crumbled and fallen away) was from one fourth to one half an inch 
thick, of the appearance of crumbling plaster, and, as in the other 
cases, it consisted of the sponge before named, with but a small 
proportion of intruded material. 
While considering the effect of the presence of so large a sponge- 
growth at the very inlet to the supply-pumps, Mr. Potts stated that 
this particular species was conspicuous among the known North- 
American sponges by its great relative density and the small propor- 
tion of its sarcode or flesh. Its decay, therefore, at the termination 
