ULOTHRIX. 135 



Attached to stones in streamlets. A form not infrequent, 

 but am not convinced that it may not be a young condition 

 of U. zonata. 



ULOTHRIX SPECIOSA, Carm. 



Filaments robust, soft, straight when young, becoming 

 curled at maturity, 2-4 inches long, growing in flowing or 

 spreading tufts, attached to rocks ; cells about half the length 

 of the diameter, at first nearly filled with chlorophyl which 

 condenses into oblong, or nearly spherical, macrozoospores 

 which then escape. Diameter of filaments including the 

 gelatinous investment, 38-50 yw ; cells, 25-28 ju. 



Syn. Hormotrichum speciosum, Crouan. ; Lyngbya speciosa, Carm. ; 

 Ulothrix flacca, Thur. 

 Brackish and fresh-water. 



Plate CXVII, figs. 23-25, parts of filaments in ordinary 

 condition ; fig. 26, partly empty cells from which the macro- 

 zoospores escaped. 



Hormotrichum ( Ulothrix) Carniichaeliij Harv. , is very nearly 

 allied to this species. 



ULOTHRIX YOUNGANUM, Dillw. 



Filaments of a bright green color, 1-3 inches long, erect, 

 straight or curved, slightly gelatinous ; cells varying in 

 length from nearly twice as long as wide, to one-half or one- 

 third of the diameter. Filaments of irregular size, from 

 20-30 IJL in diameter. Smaller than the preceding. 



Syn. Conferva Youngana, Dillw. ; Hormotrichum Youngeanum, 

 Kg. ; Ulothrix isogona, Thur. 



Plate CXVII, figs. 20-22, parts of a younger filament and 

 two parts of older plants, having undergone two or three 

 divisions of cells. 



From submarine waters, Massachusetts. 



ULOTHRIX SUBTILIS, Kg. 



Denizens of fresh -water, bright or paler green ; cells 

 usually as long, to twice as long as wide. 



The following have been arranged as varieties of this species : 



a. typica, Kirch. Cells, 5-6 ^ diameters ; as long or slightly 



longer, 

 b. subtilissima, Rab. Cells, 44-47 jn diameter ; 1-2 times as 



long, rarely 3-4 times longer. 



