\ 
148 NOVA SCOTIA FRESH-WATER SPONGES— MACKAY. 
character of the discovery, I had unwittingly mixed up with SV. 
lacustroides. However, I discovered none of its stellbate biro- 
tules, and neither Mr. Carter nor Mr. Potts, of Philadelphia, 
have observed any evidence of the existence of this species in 
lacustrine deposits sent them. 
Meyenia Leidii, Carter—Slide No. 10 contains the skeletal, 
flesh and small birotulate statoblast spicules obtained by the 
acid treatment from this sponge which comes from the Schuyl- 
kill, Philadelphia. A few birotules like this have been observed 
in the lake deposits, from which the presence of the species is 
inferred. I have not been fortunate in securing one in any of 
my mounts. 
Meyenia craterrforma—Slide No. 12 shows the spicules of 
this species, the large hooked birotules being in great numbers. 
This also comes from the Schuylkill. A few birotules like these 
have also been observed in the deposits alluded to, but so rare 
that none happen to be in any of my mouits. 
Meyenia Hverettt, Mills—Birotulate spicules, identical with 
those of this species, are found one in each mount on an average 
in the Halifax Water Lake deposits, which I received from 
Professor Lawson. Slide No. 15 contains one if not two near 
the right hand lower margin of the cover. It is smaller than 
the birotule of M. crateriforma, with the shaft quite smooth. 
Slide No. 84 contains 14 skeletal spicules of the most common 
form from Earltown lakes, arranged in the two lower lines of 
the lower right hand rectangle. Accompanying the slides which 
explain themselves is a small box with dried portions of S. /acu- 
stroides and some of the fresh water deposits from both 
Mackintosh lake and the Earltown lake. The amount of silica 
derived from these waters and formed into diatom cells and 
sponge spicules must be very great, as the deposits are in some 
places very many feet in depth. 

NotE—Since the above paper was presented, the author has 
observed nine species of freshwater sponges, (four genera) living 
in the lakes of Nova Scotia. Of these, two, viz., Spongilla Mace- 
Kayii, Carter, and Heteromeyenia Prctovensis, Potts, are new to 
science. They will appear in next year’s Transactions, 
