110 rniversity of California Publications in Botany [Vol.8 



"Stigonemataceae" is orthographically correct and is more according 

 to custom than ''Stigonemaceae" adopted by Forti 1907, p. 562. 



"We have increased the scope of the family by removing from the 

 Rivulariaceae the genus Brachytrichia and placing it here. Although 

 the species of this genus have trichomes with terminal hairs, yet so do 

 the trichomes of Mastigocoleus, which is assigned to this family by 

 Bornet and Flahault {loc. cit., pp. 53, 54). The branching in Mastigo- 

 coleus is mainly true branching but the piliferous branches appear 

 to be false. From our point of view the branching in Brachytrichia 

 is always true branching and we place it in Stigonemataceae near 

 Mastigocoleus and Nostochopsis. 



The majority of the Stigonemataceae are terrestrial or inhabitants 

 of the fresh waters. Only two genera are made up of marine species. 



Key to the Genera. 



1. Sheaths not diffluent, shell or lime rock borers 29. Mastigocoleus (p 110) 



1. Sheaths diffluent into a definite gelatinous thallus, not boring 



30. Brachytrichia (p 111) 



29. Mastigocoleus Lagerh. 



Filaments associated into tangled masses, branching freely and 

 boring into the shells of various mollusks or into lime rock, mostly 

 single within a sheath and of uniform diameter, or at times two or 

 more within the same sheath and attenuated into long hyaline hairs, 

 generally extending beyond the surface ; branching mostly true, but 

 double piliferous branches false ; heterocysts single, terminal, or on 

 short lateral branches ; hormogonia formed in the piliferous branches. 



Lagerheim, Note sur le Mastig., 1886, p. 65. 



The single species thus far described for the genus Mastigocoleus 

 inhabits dead shells of bivalves, boring its way into the calcareous 

 material or sometimes boring into calcareous clififs. Two sorts of 

 branches occur, some bearing hairs and some devoid of hairs. The 

 former are hormogonial and are often formed two in the same sheath 

 and are false, after the fashion of the branching in Scytonema. The 

 hair bearing, or piliferous branches reach to the surface of the shell. 

 At the bases the true branches arise from a V-shaped structure similar 

 to that of Brachytrichia. 



The nniltiplieation in Mastigocoleus is, according to Bornet and 

 Flahault (1889, ]). 17) entirely by hormogonia, the coccogonioid multi- 

 plication attributed to it by Lagerheim being founded on certain 

 states of the associated species of Ilyella. 



