124 DUBLIN UNIVERSITY 



Closterium Ehrenbergii (Menegk.), not uncommon. 



„ moniliferum (Ehr.), „ 



„ Jenneri (Ralfs), rare. 



„ intermedium (Ralfs), rare. 



„ angustatum (Kiltz.), not uncommon. 



„ lineatum (Ehr.), not uncommon. 



,, setaceum {Ehr.), not rare. 



„ acutum (Brtb.), not rare. 



„ juncidum /3 {Ralfs), rare. 



Spirotaenia obscura (Rolfs), rare. 

 Pediastrum pertusum {Kiitz.), rare. 

 Scenedesmus acutus (Met/en), not rare. 



NOTICE OF THE OCCURRENCE NEAR DUBLIN OF A UNICELLULAR ALGA, 

 BELIEVED TO BE ALLIED TO THAT ALLUDED TO BY M. HOFMEISTER 

 ("ANN. NAT. HIST.," THIRD SERIES, VOL. I., NO. 1, JANUARY, 1858), " ON 

 THE PROPAGATION OF THE DESMIDI^ AND DIATOME.E." 



Appended to a Catalogue of Desmidiaceae appears not an inappropriate 

 place to record the occurrence in our district of an unicellular plant, 

 which, but for one reason, I think there might not otherwise be much 

 difficulty in concluding to be the same as that alluded to by M. Hofineister 

 in the paper to which I have before adverted, and which organism he 

 seems inclined to refer, very doubtfully, to this family. The plant met 

 with here consists of a rather large, perfectly spherical cell, containing 

 abundant and large smoothly denned chlorophyll-granules (which appear 

 often as if containing one within the other, shell within shell, to the 

 number of two or three), a scattered layer of which appears to line the 

 internal wall of the cell, while others are distributed within in scat- 

 tered rows (sometimes almost as if in broken, interrupted planes) radi- 

 ating either from the central point of the cell, or, as it appears to me, 

 sometimes as it were from a central axis, — thus often giving, more 

 especially when viewed under low powers, a somewhat stellate appear- 

 ance to the contents (see Fig. 17). The contents, however, are not 

 unfrequently irregularly scattered. So far, this description appears to 

 apply equally to the Leipsic and Dublin plants. In the plant met with 

 here there usually appears a darkish (under a low power almost black) 

 central mass. This, with the whole of the remainder of the endochrome, 



