Myxophyceae 277 



Plant mass caespitose, erect, pulvinately expanded, olive or black; fila- 

 ments 12-15 i^'c. in diameter (in the ultimate branches), up to 2 cm. in 

 length, slightly flexuous; false branches very long, equal; sheaths close, 

 thin, uniform, hyaline or yellowish; trichomes 10-15 ^c. in diameter, not 

 constricted at joints, tapering into a hair; cells quadrate or longer than 

 their diameter; cell contents blue-green or olive; heterocysts basal, often 

 in pairs. 



West Indies. Guadeloupe. (Maze). 



506. Dichothrix compacta (Agardh?) Bornet and Flahault. Revis. des Nos- 

 toc. Ann. Sci. Nat. Bot. VII. 3: 378. 1886. De Toni. Syll. Algar. 

 5. 643. 1907. 



Setchell. Notes on Cyanophyceae. — III. Erythea. 7: 45. 1899. 



Plant mass caespitose; filaments 9-12 mic. in diameter, up to i mm. in 

 length, very densely aggregated, erect, penicillate; the upper false branches 

 appressed, often included, for some distance within the common tegument; 

 sheaths lamellose, smooth, uniform or ocreate, orange becoming brownish; 

 ocreae dilated and torn at the apex; trichomes 6 mic. in diameter, ending 

 in a hair at the apex; cells as long as broad, or half as long; cell contents 

 pale olive; heterocysts basal. 



California. San Bernardino. (Parish). 



"D ichothrix compacta (Ag.) B. and F. is not always readily to 

 be distinguished from D. gy p s o p h i 1 a. It is said to resemble C a 1 o- 

 thrix parietinain every way except that it has the branching of the 

 genus Dichothrix. It is shorter than D. gypsophila, and has the 

 cells of the trichome usually shorter, rather than longer, than broad. * =^ * 

 The sheaths are yellowish-brown, lamellose, more or less dilated towards 

 the summit, but, at the very summit, are usually contracted again very 

 suddenly." — Setchell. 



507. Dichothrix meneghiniana (Kuetzing) De Toni. Syll. Algar. 5: 641. 

 1907. 

 WoUe. Fresh Water Algae. Bull. Torr. Bot. Club. 6: 284. 1879. (S c h i- 

 zosiphon meneghinianus Kuetz.); Fresh-Water Algae U. S. 238. 

 pi 170 f S-7. 1887. WoUe and Martindale. Algae. Britten's Catalogue of 

 Plants' found in New Jersey. Geol. Surv. N. J. 2: 603. 1889. (Calothrix 

 meneghiniana Kirchn.) . 



Plate XIX. fig. I. 



Plant mass composed of small deep blue-green or green dense tufts; 

 filaments 13 mic. in diameter, short, simple in the beginning, later much 

 and compactly branched; sheaths distinfctly lamellose, yellow or brown in 

 lower portions, colorless and torn into fine fibres at the apices; trichomes 

 65-75 mic. in diameter; cells somewhat quadrate, or twice as short as the 

 diameter; heterocysts usually single, about as large as the cells. 



New Jersey. Frequent on submerged wood in fresh water. (Wolle). 

 Florida. Forming a gelatinous stratum on old wet wood. (Smith). 



