216 Proceedings of the Royal Irish Academij. 



Spongilla lactistris, the other was named TiibeUa pcnnsijlvanica Potts. An 

 examination of one of Dr. Annamlale's slides of the hatter sjjecies in the 

 Britisli Museum showed that the sponge from whicli the preparation was 

 made was undoubtedly the lake form of Hekromci/cnia Ixydcri. Unfortunately 

 geinmules were not present, and I have not succeeded in procuring any 

 further specimens of the sponge from Scotland. 



Habitat k^d Genekal Distkibution of 1'UEsh-watek Sponges ln 



Ireland. 



Fresh-water sponges occur throughout Ireland in lakes, ponds, rivers, and 

 streams. They also occur iu the canals, in old quany-holes, and even in 

 bog-draius. They are to be found in mountain tarns and streams up to a 

 height of 2,200 feet, as well as iu the largest lakes and rivers of the lowlands. 



Iu this country fresh-water sponges usually grow on and under stones, 

 but they also grow on water-plants, and, in lowland rivers, they have been 

 found on the submerged rooU of trees, such as the alder, and on rotting, 

 submerged tree-stumps and branches. With regard to lakes,, sponges arc 

 most abundant in those which have rocky or stony shores, or have at least a 

 stretch of stone-strewn beach, but they also grow, though never luxuriantly, 

 in lakes which are almost entirely surrounded by high banks of peat, and in 

 which the water is deep-brown in colour from the peat. In these lakes on 

 the bogs the sponges are occasionally found on the submerged stumps of the 

 trees (for the most part Scotch Fir) that iu former times grew in abundance 

 in areas now covered by bogs and lakes. Sponges have even been seen 

 growing on a sod of turf lying under water in a stream. 



When the bottom consists of mud, the " chief enemy " of sponges, they 

 grow raised above it on the stems of reeds or other water-plants, or on the 

 stone-work and wood-work of the walls of mill-streams, canal locks, and 

 other artificially constnicled waterways. 



Fresh-water spongea are occasionally found iu brackish water in difl'erent 

 parts of the world. So far they have not lieen found in brackish water in 

 Ireland, although search has been specially made for them. For example, 

 the tidal river which drains Furnace Lough, Co. Mayo, was carefully 

 examined, but without success, as well as the southern end of the lake where, 

 the water is brackish. Sponges were abundant in fresh water at the 

 northern end of the lake. On the other hand, a marine species of I'olyzoa 

 Mcmbraniporn mcmbraiuicai,vi\\\(i\\ establishes itself readily in brackish water, 

 was found all along the river, in the southern part of the lake, and even in 

 fresh water at the northern end, where it grew in company with Ephydatia 

 /luviaiUu. 



