The Fresh-water Spo?iges of Ireland. 129 



Habitat: Lough Doon, near Dingle, 1,000 feet above sea-level (R. I. A 

 Flora and Fauna Committee). — United States : from Florida to Nova 

 Scotia, and from the Atlantic coast to Iowa. (Potts, 7, p. 243). 



The Irish specimens are in shape of small thin patches, i or 2 mm. in 

 thickness, one of them with a conical elevation 4 mm. in height, bearing 

 an osculum on its side. In giving the dimensions of the spicules we add 

 Potts's measurements in brackets: skeleton-spicules 0*22 by o-oo8 to 

 0-0I2 mm. (Potts 0*317 by o"oi5 mm.); long amphidiscs 0*052 by 0-005 

 mm. (Potts 0*0507 by 0*006 mm.) ; short amphidiscs 0*024 mm. (Potts 

 0*03 mm.). 



Tubella, Carter. 



Skeleton-spicules smooth or spined, pointed or rounded off at the 

 extremities. Gemmules with unequal trumpet-shaped amphidiscs of 

 which the larger rotule rests upon the chitinous coat. The margins of 

 these larger rotules generally entire. 



Tubella pennsylvanica, Potts. Gray or green. Minute, encrust- 

 ing. Skeleton-spicules extremely variable as to length and curvature ; 

 rounded or pointed at the ends ; entirely spined. Margin of the large 

 rotule of the amphidiscs entire, that of the small rotule occasionally 

 notched. 



Habitat : Columbkille Lough, Ballyshanuon, 100 feet above sea level 

 (Dr. R. H. Creighton^y United States ; Lehigh River and tributaries ; 

 also generally throughout the Eastern United States (Potts, 7, p. 251). 



The largest of the Irish specimens is an encrusting mass, 25 by 20 mm. 

 and 7 mm. in height, with a corrugated but smooth surface, bearing 8 

 or 9 oscula with a diameter of i mm. or less. Three varieties of skeleton- 

 spicules can be distinguished : (i) strongly spined, curved spicules, with 

 blunt ends, which are as a rule the thicker, the shorter, from 0*07 by 

 0*018 mm. to 0*116 by 0*013 mm. (2) Slightly spined, curved or 

 straight spicules with pointed ends, of pretty uniform dimensions, 

 0*16 by 0*005 mm. to 0*19 by o'ooS mm. (3) Slightly spined, shylote 

 spicules, few in number, 0*15 by 0*005 mm, Potts gives the average of 

 the skeleton spicules as 0*165 by 0*0075 mm. 



The specimens upon which this account is based, are not 

 the outcome of systematic investigation. What results such 

 an investigation would bring is difficult to foresee. But I am 

 sure that even the highest expectations would not be 

 disappointed, and I would not be surprised if the majority of 

 American Spongillidse were discovered some day in the West 

 of Ireland. A fresh-water station after the model of those in 

 Germany and Bohemia would be the best means towards the 

 study of the remarkable Fauna and Flora of Western Ireland. 



I will not conclude this paper without expressing my great 

 indebtedness to the following gentlemen : — Dr. Scharflf, for 



^ Erroneously recorded as Euspongilla lacusiris, Irish Nat., vol. ii., 

 p. 322. 



