156 Ulothricaceae 



Bright green, growing in short tufts or long tangled skeins ; 

 cells cylindrical with strongly thickened outer wall, 10-25//. in 

 diameter, %-% as long, the septations thin ; chlorophyll-band 

 rilling the length of the cell, containing (in the vegetative condi- 

 tion) one distinct pyrenoid ; when the cell contents are preparing 

 for formation of zoospores, many pyrenoids may be seen in a cell 

 (/>/. 20, f. 7-p). 



Exsic. : Phyc. Bor. Am. 77, Nahant, Mass., March, 1891. 

 (W. A. Setchell). Alg. Exsic. Am. Bor. Mystic River, Maiden, 

 Mass. (F. S. Collins). Hauck & Richt, Phyk. Univ. 720. Mystic 

 River, Mass., March, 1889 (F. S. Collins). 



On Fticus and on leaves and culms of Spartina, etc. (rarely on 

 rocks), between tide limits. Common on the New England coast 

 and in New Jersey, at least as far south as Atlantic City. 



Maine: Seguin Island, Aug. 30, 1900 (M. A. Howe, 2j8). 



Connecticut: Bridgeport, May (571). 



New York: Pelham Bay, April (12), April 18, 1901 (M. A. 

 Howe); College Point, February (250, 251); Rosebank, Staten 

 Island, December (231, 240) ; Livingston, April (326). 



New Jersey: UnderclifT, Bergen county, April (310, 533); 

 Atlantic City, Dec. 25, 1888 (I. Martindale). 



This species is very generally found growing on Fticus ; on 

 only one occasion have we seen it on rocks and shells. In this 

 respect it is opposed to Hormiscia penicilliformis ( Urospord) which 

 is always found on rocks and timber, and never, so far as is known 

 to us, on Fticus or grasses. Professor Wille ('ot) states that at 

 Drobak U. flacca is found only on stones and rocks. He has created 

 a new species, U. pseudoflacca, which seems to be distinguished from 

 this only by such slight physiological or reproductive character- 

 istics that we fail to see how he can determine which is the original 

 U. flacca. Physiological characters are sometimes of importance, 

 but it is questionable whether consistency would not demand the 

 abandonment of the name U. flacca quite as much as that of U. 

 implexa. 



Like most fresh water forms, this species usually disappears 

 during the summer, but it probably forms a more luxuriant growth 

 in late autumn and winter, while the fresh water forms do not de- 

 velop extensively except in spring. 



