DUBLIN UNIVERSITY ZOOLOGICAL AND BOTANICAL ASSOCIATION. 39 



Staurastruni margaritaceum (E.), rare. 



punctulatum {Br eh.), not uncommon, 

 hirsutum (Ehr.), common. 



teliferum ( ), rare. 



polymorphum (Breb.), not uncommon, 

 tricorne (Breb.), common, 

 controversum (Breb.), not uncommon, 

 paradoxum (Meyen), ,, 



brachiatum ( ), rare. 



alternans (Breb.), „ 

 asperum /3 (Breb.), „ 



[I have met with a form of Staurastruni bearing some 

 resemblance to 8. spinosum, or rather between that spe- 

 cies and S. avicula. The spines at the angles are forked 

 to the base, and not merely at the extremities, and the 

 intermediate spines are smaller than S. spinosum. The 

 form agrees much better with the figure of S. avicula, 

 provided that species had intermediate spines, than with 

 that of S. spinosum. It is not uncommon, according to 

 my experience, in the district to which this list apper- 

 tains.] 

 Didymocladon furcigerus a, (Breb.), rare. [Slow stream between Round- 

 wood and Devil's Glen. May be more common, however.] 

 Tetmemorus Brebissonii (Menegh.), common. 



,, granulatus (Breb.) very common. 



Penium margaritaceum (Ehr.), not uncommon. 

 ,, cylindrus (Ehr.), „ 



,, digitus (Ehr.), very common. 

 ,, Erebissonii (Menegh.), „ 



,, closterioides ( ), rare. 



Docidium nodulosum (Breb.), not uncommon. 

 ,, truncatum (Breb.), ,, 



,, clavatum (Kutz.), ,, 



,, Ehrenbergii ( ), common. 



,, asperum (Breb.), rare. [Should a master-hand ever propose 



the erection of a new genus for the reception of this spe- 

 cies, or its removal from Docidium, the step would meet 

 with my approval. To my mind it is not a Docidium : it 

 entirely wants the characteristic constriction of that genus, 

 and I have looked carefully, but in vain, as Mr. Ealfs did, 

 for terminal moving globules. I have found occasionally 

 three or more individuals adhering end to end, like a fila- 

 mentous conferva, with extremely long cells. The speci- 

 mens I have met with were rather more dilated at the ends 

 than is represented in Ealfs' figures.] 

 Closterium lunula (Mutter), common. [This is a favourable species for 

 observing the circulation. It is not, however, like that 

 phenomenon in other vegetable cells, the current being 



