146 NOVA SCOTIA FRESH-WATER SPONGES—MACKAY. 
island in the centre of the lake, I found green sponges branching 
out four or five inches. The external configuration of this 
sponge was sufficient to point it out as Spongilla lacustroides, 
Potts, the American form of the European 8S. lacustiis, which it 
much resembles. The deposit in the lake was chiefly composed 
of the exquisitely sculptured silicious cells of over fifty different 
species of diatoms to which I shall specially refer in another 
paper, mingled with a great number of the skeletal and other 
spicules of more than one species of silicious sponge. Among 
the plants of the higher orders the waters had an abundant 
supply of Potamogeton, namely, P. natans L. and Var. prolixus 
Koch., P. praelongus, Wulfen, and P. obtusifolvus, Mertens and 
Koch., and Naias flealis, Rostk, of the same family, and of the 
Gentian family, Limnanthemim lacinosim, Grisebach, with its 
floating, heart-shaped leaves, while eriocaulow septangulare 
Withering, and Lobelia Dortmana, L., studded the shallows. In 
the Earltown lakes the following were, in addition, plentifully 
found: Raninculus aquatiliso, Var., trichophyllus, Chaix, and 
Chara fragilis. Also, near by, in a pond just below McKay’s 
mills, a luxuriant mass of Nitella flexilis was found. The 
altitude of this position will be probably not very far from 1000 
feet above the sea level. Mackintosh Lake, which is a little 
lower, and on the north-eastern side of the water shed, is most 
easily accessible from Pictou County, near the boundary of 
which it is situated, a few miles above Loganville, on the West 
Branch of River John, yet in the County of Colchester. The 
waters of both lakes are very clear, and the drift around the 
Mackintosh especially, is characterized by the presence of 
granite. 
I have had but little time to follow out the collection and 
study of the sponges since the accidental discovery alluded to. I 
shall therefore throw this paper into the form of notes, or of a 
report of progress, hoping to be able to give more complete in- 
formation by the end of another year. I shall now simply des- 
cribe the freshwater sponge as a mass of reticulated or 
channelled sarcode, green, when exposed to the influence of the 
light, supported by a framework of interlaced silicious spicules, 
