MEKISMOPEDIA. 299 



waved and curled, very variable in breadth. Granules qua- 

 ternate, closely covering the frond, set in longitudinal lines, of 

 which two or more (sometimes half a dozen) form the breadth 

 of the frond ; interstices colourless." Harv. 



Kiitzing makes a new genus for this species under the 

 name of Prasiola. 



4. ULVA BINALIS Hass. 

 Char. Cells large, in twos. 



I have not studied this species with sufficient attention to 

 pronounce decidedly whether it is distinct or not ; the ar- 

 rangement of the granules by twos would seem, however, to 

 be remarkable, and to render it very probable that it really is 

 so. This species would appear to be referred to in the fol- 

 lowing remarks of Vaucher's " Hist, des Conf." p. 238. " It 

 is not impossible but that other species of freshwater Ulvce 

 exist independently of those which I have described. I have 

 myself met with some others which have appeared to me to be 

 different from the two first ; one in particular, the grains of 

 which were disposed two by two, and not four by four ; but I 

 pass them by under silence, because I am not assured whether 

 they are species or only varieties." 



40. MEKISMOPEDIA. 



Char. Frond increasing by spontaneous division, laminar, 

 quadrangular. 



Derivation. From fjuspicr/jios, a division, and TrsSiov, a 

 fetter or chain. 



1. MERISMOPEDIA PTJNCTATA Meyen. 

 Plate LXXXIV. Fig. 6. 



Char. " Green, corpuscles imbedded in a crystalline mem- 

 brane, and nearly the T |^ of a millimetre in size, polypary, 

 quadrangular, flattened, sometimes twice as broad as long, 

 equalling from the T ~ to ^ of a millimetre, and containing 

 sixteen simple corpuscles, either binary or quaternary." 

 Ehr. 



