Myxonema 197 



relation to his Draparnaldia tenuis, at one time making the latter 

 a synonym under Conferva lubrica, and again making Conferva 

 Inbrica a variety of D. tenuis. After a very extended study of both 

 these forms, there is no question in our opinion, of their distinct- 

 ness, and we believe there is no doubt as to the correctness of the 

 determination of the two as here described. Certainly there is no 

 other American form that can be identified with Dillwyn's Con- 

 ferva lubrica. 



Kiitzing's figure of this species is only fair, and Berthold seems 

 to be the only author who has particularly noted and correctly 

 illustrated the small branch- bearing cells that are so characteristic 

 of this and the rest of the forms of this group, though others 

 have noted them in Stigeoclonium flagelliferum, and Kiitzing has 

 given a hint of their presence in several forms. Miss Tilden ('96) 

 has stated that, to her knowledge, such cells are a characteristic 

 of no other species besides S. flagelliferum ; possibly this is an in- 

 dication that the western algal flora is considerably different from 

 that of the east, for here there are at least seven well-marked 

 forms in which these cells are a prominent feature. 



Mvxonema lubricum may in some sense be considered a standard 

 or point of departure for the comparison of the other forms of this 

 group. Though it reaches a greater length than any of the other 

 members of the group, they are for the most part more developed 

 in some feature. The variety varians is smaller but rather more 

 branched ; M. subuligerum has shorter cells, but more divergent 

 and sharp-pointed branchlets ; M. amoenum differs chiefly in the 

 long cells of the main branches ; M. flagelliferum might be con- 

 sidered a form of the last with attenuated, setiferous branchlets ; 

 M. ventricosum is a form in which the main cells are lengthened 

 and inflated. These do not form an entirely progressive series, 

 but are clearly related to M. lubricum. M. tenue is a much finer 

 and somewhat simpler form, and might well be placed in the an- 

 cestral line of M. lubricum. The probable developmental relation- 

 ship would be better indicated if the alternate branched species 

 were placed first and M. tenue made to form a connecting link 

 with the larger forms of the lubricum group. The present arrange- 

 ment is simply more convenient for comparison. 



