192 Chaetophoraceae 



Forming a furry coating on dead straws and leaves, in stagnant 

 water and in running water of a watering-trough ; also in tufts on 

 the sides of a rocky spring. 



Connecticut: Plymouth, March (524). 



New York: East Chester, May (392B) ; Central Park, June 



(613B). 



The opinion expressed by Schmidle that this species is quite 

 distinct from M. Kuetzingianurn is abundantly confirmed by com- 

 parison of American specimens. Most of the specimens on which 

 the above description is based agree quite exactly with Raben- 

 horst's type material (Alg. Sachs. 829). The length of the cells 

 as here given is greater than that given by Schmidle, but hardly 

 greater then in some of Rabenhorst's plants. 



The plants from Central Park are rather shorter and finer, so 

 that we at first identified them as Microthamnion vexator Cooke 

 (Grevillea, 11: 75. 1882; Brit. F. W. Alg. 188. pi. 73. f. 1. 

 1883), but they are marked by a very strict or appressed habit of 

 branching, while Cooke's figures represent a plant with very open 

 branching. We have, therefore, included these plants in M. stric- 

 tissimum, for there is no divergent character of sufficient importance 

 to warrant making a new form. Indeed it is probable that M. 

 vexator should not be maintained even as a variety of M. strictissi- 

 mnm, for though Cooke states that his plant is very much more 

 slender than the latter species, the diameter he gives (3 /1) is not 

 less than that of many plants of M. strictissimum. Furthermore, 

 the measurements of M. vexator based on Cooke's original speci- 

 mens, as given by Nordstedt (Svensk. Vet. Akad. Hand. 22 s : 15. 

 1888), are so similar to those of the type material of M. strictissi- 

 mum, that we fail to see how it is possible to separate the two forms. 



Microthamnion strictissimum macrocystis Schmidle, Hedwigia, 

 38: 169.//. 7./. i-j. 1899 



Plants 300-800 fi tall, branching more open ; branchlets as- 

 cending or spreading, slender, and tapering slightly toward the 

 end; cells 2.5—3/^ (rarely 4/2 below) in diameter, 6-12, or 20 

 times as long ; chromatophore pale and narrow, not encircling the 

 cell, the tips of the apical cells hyaline [pi. 27, f. 1). 



