232 Proceedings of the tioyal Irish Academl/. 



Mayo. —Furnace L., L. Beltia, Knappaghmoie L., Moher Tj., L. Nacorra. 



Sligo.— L. Gill (43), L Arrow, Dargan L. (coll. A. W. Stelfox). 



Fermanagh. — L. Scolban and Garvay E. (coll. Major Trevelyan). 



Down. — Stream at Saintlield, canal at Hillsborough (coll. N. H. Foster). 



Antrim. — Lagan Canal and disused reservoir near Cave Hill (coll. W. H. 

 Patterson). 



Derrv. — Emigh L. (coll. D. C. Campbell), E. Bann between Deny and 

 Antrim (coll. K. A. Phillips and A. W. Stelfox). 



Ephydatia fluviatilis (auct.) var. (PI. XXVI, figs. 4-9). 



Certain sponges have been collected in the west and south of Ireland 

 which have proved ditlicult to determine, as the skeleton-.spicules vary a good 

 deal in the specimens from the diHerent localities, and gemmules have not 

 4>een found, although nearly all the examples were taken in the late summer. 

 The sponges usually grew in great abundance at a given locality, and as 

 many as one hundred specimens have been preserved from a single spot. 

 The skeleton-spicules of these sponges are short, often very thick oxea, the 

 majority in one specimen spined to their tips, in another smooth. Examples 

 collected in two localities, namely, in the DrumelifT Kiver <lraining Glencar 

 Lough, ('ounty Sligo, and in the Itiver IJoyle below Oakport Lough, County 

 Koscommon, seem to offer a clue to their identity. 



The skeleton-spicules varj- in an unusual degree in the sponges from these 

 two rivers, more i)articularly in thase from the Drumelin' River, some of them 

 being very similar to the spicules just alluded to. Although gemmules were 

 not found, yet a fair number of scattered amphidiscs are to be seen in the 

 spicule preparations. These amphidi.scs qmte agree with the conesponding 

 spicules of typical specimens of Ephydntia fiuviatilis. It has been concluded, 

 therefore, that the foregoing sponges represent a variety or phase or race of 

 E. JtuviaiUis which does not produce gemmules, or at least produces them 

 with extreme rarity, and whicii possesses, to the exclusion of the more 

 typical skeleton-spicules, one or other form, such as occurs a.s an occasional 

 abnormality in typical specimens of £. Jluviatilis. The abnormal spicules, 

 which occur only occasionally in some specimens, may occur in numbers in 

 others, which undoubtedly are quite typical of that species. For convenience, 

 these peculiar sponges are referred to as E. fluviatilis, var. 



The sponges, including those from the above-mentioned rivers, agree in 

 external appearance. They form thin, more or less circular, patches on the 

 upper and under surfaces of stones ; they are very hard to the touch, their 

 surface is even, but is seen under the lens to be min\itely hispid from the 

 tips of the terminal spicules of the main skeleton-fibres, which project very 



