1-'19J SetcheU-Gardncr : Myxophyceae 85 



The trichomes of species of Ifijdrocoleiim are always capitate while 

 those of the other two genera are rarely so, the exception being one 

 species of Microcoleus. 



Hydrocoleiim lyng'byaceum Kuotz. 



riate 1, fig. 10 



Plant mass forming a smooth, compact, mucous stratum, or some- 

 times caespitose when 3'oung ; filaments unbranched below, but with 

 numerous false branches above ; sheaths wide, irregular, apices 

 acuminate, varying often to open, sometimes completely diffluent ; 

 trichomes dark blue-green, numerous at the base of the filaments, 

 usually solitar.y in llic l)raiie]ios, sometimes spirally twisted, 8-16/* 

 diani., tapering and truncate at the apices ; cells 2.5-4.5/a long, dis- 

 sepiments granular. 



Forming a thin layer of considerable extent on piles, in the middle 

 littoral belt. Lands End, San Francisco, California. 



Kuetzing, Sp. Alg., ]849fl, p. 259; Gomont, Monogr. des Oscill., 

 1892, p. 337, pi. 12, figs. 8-10 (1893, p. 75, Kepr.). 



Thus far a single species of Jlydrocoleum from a single locality 

 has been found on our coast. It seems referable to the var. rupestre 

 Kuetz. {loc. cit.), of which the type locality is the shores of Calvados 

 in northern France. Our specimens seem to agree well with the 

 descriptions and figures. 



22. Microcoleus Desm. 



Trichomes numerous, within a common, firm, hj^aline, c^dindrical 

 sheath ; sheath usually unbranched and tapering at both ends ; filaments 

 forming denselj^ intertwined, more or less diffluent, masses on earth, 

 in salt water or in fresli water; trichomes attenuate, with straight 

 apices, tiglitly interwoven within the sheath ; apical cells acute or 

 rarely obtuse, conical or capitate. 



Desmazieres, Cat. des plantes, 1823, p. 7. 



"VVe have followed Gomont in retaining the name Microcoleus of 

 Desmazieres (1823) as against that of Vaginaria Bory (or Gray) 1821. 

 The original Vaginaria Rich (in Persoon, Synopsis, 1805, p. 70) has 

 passed, at least seemingly, into the synonymy of Fuirena Rootb. Bory 

 later (1826, p. 524) adopted Microcoleus in jilace of his Vaginaria. 

 The decision of Gomont, liowever, settles the case according to the 



