20 Mr. E. Potts on the wide Distribution of 



Hab. Freshwater. 



Loc. Mackay's Lake, near Pictou, Nova Scotia. 



Obs. The most remarkable point presented by this species 

 is that its flesh-spicule should be identical with that of Mey- 

 enia Everetti y whose statoblast is covered with a thick crust of 

 long and large birotules, denticulated, with recurved teeth 

 like those of Meyenia Baileyi &c, showing that this kind of 

 flesh-spicule may be present in totally different species of 

 freshwater sponges, unless it should be owing to the presence 

 and proximity of M. Everetti, which, as above stated, grows 

 in the same lake. 



It is remarkable, too, that the spiculation of SpongiUa 

 Mackayij both skeletal and flesh-, should be almost identical 

 with those which I have described and illustrated of the 

 freshwater sponge-spicules so abundant in the diluvial deposits 

 of the Altmiihl valley, in Bavaria (' Annals,' Nov. 1883, 

 vol. xii. p. 329 &c, pi. xiv. fig. 18, a, b } g } h } i). 



IV. — On the wide Distribution of some American Freshwater 

 Sponges. By E. POTTS *. 



Allusion having been made to the wide distribution of 

 certain species of spiders over the North-American continent, 

 Mr. E. Potts, referring to the freshwater sponge-fauna of this 

 country, said that SpongiUa fragilis, the first species named 

 in America, described by Dr. Leidy in 1851 from specimens 

 collected near Philadelphia, had since been found abundantly 

 along the Atlantic coast from Florida to Nova Scotia. It 

 had been gathered at several points along the St. Lawrence 

 and in the great lakes through the middle continent, and in 

 the far west had been described by Dr. Bowerbank, in 1863, 

 under the name of S. Lordii, as found in the lakes and streams 

 flowing from the Cascade Range in British Columbia, affluents 

 of the majestic Columbia river. The species may therefore 

 be regarded as strictly continental in its range, and until very 

 recently it has bten distinctively American. It is a little 

 singular that the only other place in which it has been noticed 

 is in the neighbourhood of Charkow, in Russia, where it was 

 discovered a few months since by Dr. L. Dybowski. 



The specimens of this species from Nova Scotia had been 

 collected by Mr. A. H. MacKay, B.A., B.Sc, of Pictou 



* Proc. Acad. Nat. Sci. Philadelphia, 2nd Sept. 1884, p. 215. Reprinted 

 from a copy sent by the author to Mr. H. J. Carter, F.li.S. 





