DUBLIN UNIVERSITY ZOOLOGICAL AND BOTANICAL ASSOCIATION. 37 



we not expect to find the Desmidiacese in greater myriads in the waters 

 they frequent than they really are? I have noticed the movement equally 

 active in both the old and newly formed segments, and while even yet 

 undergoing the process of division. I regret I have been only suffici- 

 ently fortunate to meet with the true reproduction of the Sporangia in 

 these species. 



Perhaps it may not he out of place if I add, with regard to the col- 

 lection of the Desmidiaceae, that I have found the most expeditious 

 method of gathering the smaller species (which adhere, forming a cloud - 

 like mass round the leaves of plants or similar foreign objects) to be, to 

 bring a small phial under the water, gently to push the blade of grass 

 or sedge, or other such object, into it, snip it off, and thus retain the 

 Desmids adhering, rather than to strip the plant with the hands, fre- 

 quently rather a tedious and difficult process. The larger species I have 

 found more abundant, not in the deeper pools, but rather in shallow 

 water, an inch or two in depth, and in which there exists a very slight 

 trickle of water permanently throughout the summer. 



In regard to precise localities for the species mentioned in the list, 

 I regret I cannot be more definite. Along the "Piperstown Eoad to 

 Glencree," there are a number of pools, as well as on each side of the 

 " Military Eoad" over the " Feather-bed Mountain," and these, with 

 the few exceptions mentioned in the list, produced all the species which 

 I have had the pleasure to meet with. Most ponds and streams pro- 

 duce some species, especially of the genera Closterium, Cosmarium, 

 Scenedesmus, Ankistrodesmus, and others. 



LIST OF DESMIDIACE.a3 FOUND IN THE NEIGHBOURHOOD OF DUBLIN. 



Hyalotheca dissiliens {Smith), abundant. 



,, mucosa {Mert.), „ 



Didymoprium Borreri (Ralfs), not uncommon. 

 Desmidium Swartzii (Ag.), rare. 

 Sphserozosma excavatum {Ralfs), rare. 

 Micrasterias denticulata (Breb.), common. 



„ rotata (Grev.), „ 



,, papillifera (Breb.), not uncommon. 



„ Americana /3 {Ehr.), rare. 



,, oscitans (Ralfs), ,, 



,, crenata (Breb.), not uncommon. 



,, truncata {Cor da), „ 



Euastrum verrucosum {Ehr.), rare; base of " Seechon" Mountain. 



,, crassum {Breb.), not uncommon. 



,, oblongum {Grev.), common. 



,, affine {Ralfs), not uncommon. 



,, ampullaceum ( ), rare. 



,, didelta (Turp.), frequent. 



,, ansatum (E.), „ 



„ pectinatum {Breb.), not rare. 



,, rostratum {Rolfs), rare. 



