NOVA SCOTIA FRESH-WATER SPONGES—MACKAY. 147 
about the one hundredth or 12 one thousandths of an ineh in 
length. (See slides, Nos. 2, 3,5, &c.) In the sareode is another 
system of smaller generally cured and tuberculated spicules, 
averaging from 2? to 3 one thousandths of an inch. (See Nos. 
1, &c.) And thirdly, we have in the statoblasts or reproductive 
gerumules which are generally formed towards the close of the 
summer season in the body of the sponge, what are called the 
statoblast spicules, smaller than the others, forming the best 
basis for classification. I have sent specimens of the material 
collected to H. J. Carter, Esq., F. R.S., of England, the author 
of the “History and Classification of the known species of 
Spongilla,” the latest and most authoritative monograph on the 
subject. Mr. Carter kindly assisted, and sont me specimens of 
some English and American forms. The following is a summary 
of what is already known :— 
Spongilla lacustroides, Potts. —This species I have found 
growing abundantly in the Mackintosh and Earltown lakes. It 
probably also exists in the water supply lakes of Halifax, judg- 
ing from the appearance of some of the skeletal spicules 
in their deposits received through the kindness of Professor 
George Lawson, of Dalhousie College. There isa great rarity 
of statoblast spicules in the lake deposits examined. This will 
not be so surprising when it is considered that in the specimens 
of spongilla collected in August last, of which some dried 
fragments are here for examination, when treated with acid 
to destroy the organic matter, only skeletal and flesh spicules 
are to be seen, as in slides Nos. 1 and 2. Slide No. 5 
shows the spicules, all three kinds, of S. lacustris from the 
Exeter River, England, obtained from a portion of a speci- 
men sent me by Mr. Carter. The statoblast spicules are few, 
more curved, broader than, and not tapering like, the flesh 
spicules. The corresponding ones of WS. lacustroides would 
be less curved. On slide No. 3 are shown the spicules of 
another species in addition to the first named, which I was sus- 
pecting to be those of S. fluviatilis from the large tuberculated 
skeleton spines, and the impression that they had come from a 
large though not branching sponge which, from the unexpected 
