1919] Setchell-Gardner : Myxophyceae 11] 



Mastigocoleus testarum Lagerli. 



Plants forming thin membranaceous layers at first, soon boring- into 

 the shells of mollusks, pale blue-green ; filaments variously contorted ; 

 6-lOfx thick ; sheaths very delicate, hj-aline ; trichomes 3.5-6/a thick, 

 cells cj'lindrical or subcylindrical ; heterocysts elliptical or spherical, 

 6-18/i, diam. 



Growing in 03'ster shells. San Francisco Bay, California. 



Lagerheim, Note sur le Mastig., 1886, p. 65, pi. 1 ; Bornet and Fla- 

 hault. Rev. Ill, 1887, p. 54; Setchell, Notes on Cyanophyceae III, 

 1899, p. 47. 



Mastigocoleus testarum is abundant in oyster shells on the New 

 England coast. These mollusks have been introduced into San Fran- 

 cisco Bay and plants growing on these are the only reported ones in 

 our region. They are thus probably not indigenous. Something sim- 

 ilar has also been found in the thin shell of some bivalves at San Pedro, 

 California. The material, however, is scanty and fragmentary. 

 Further search and comparison is necessary to establish the true status 

 of the genus as regards our coast. 



30. Brachytrichia Zanard. 



Colonies more or less spherical, composed of a mass of filaments 

 embedded in a firm, gelatinous matrix, solid when young, later becom- 

 ing more or less inflated, somewhat cavernous, and usually plicate and 

 rugose; filaments intertwined below, giving rise to numerous erect, 

 true branches at the ends of loops, becoming parallel and attenuated 

 toward the surface of the colony ; heterocysts intercalary ; spores 

 unknown. 



Zanardini, Phye. Ind. Pug., 1872, p. 24. 



The type species is Brachytrichm rivulanoides Zanard. (1872, 

 p. 24), which is identified with the Nostoc Quoyi Ag. (1824, p. 22), the 

 type of which was collected at the Mariana Islands by Gaudichaud. 

 Zanardini 's type came from Sarawak, and this species seems more or 

 less common through the Indo-Malayan region. The Brachytrichia 

 Quoyi is large, firmly gelatinous, bullate, and dark green, while 

 certain other species are flattened and brownish. 



The branching of filaments in Brachytrichia is unique. The fila- 

 ments at first are more or less horizontal. At certain points in them 

 lateral loops are formed, sometimes only a few cells long, at other 



