358 Howe: ALGAE OF BERMUDA AND THE BAHAMAS 
sinage des Dichothrix cyanea et penicillata dont elle est d’ailleurs 
bien distincte.”’ 
Dichothrix Bornetiana is occasionally mixed with small quan- 
tities of undoubted Polythrix corymbosa and very rarely the 
agglutination of filaments in a terminal fascicle may be so 
pronounced as to suggest Polythrix. It is not impossible that 
it does represent a condition of the Polythrix, yet it is prepond- 
erantly so very different from Polythrix corymbosa that the burden 
of proof-would seem to rest with those who would assert identity. 
At least until such proof is forthcoming, it seems desirable to 
give the plant a distinctive name. 
The trichomes and filaments are coarser, (trichomes 8-14 v. 
vs. 3-7 v.) and the sheaths are thicker than in Polythrix corym- 
bosa, but increased development along these lines is perhaps 
what might be expected if the filaments of the Polythrix really 
became discrete and free. The heterocysts also are larger and 
often more elongate, the cells are commonly about one half as 
long as broad, while in P. corymbosa they often’ seem longer 
than broad, (perhaps on account of coalescence or imperfect 
definition), the trichomes are usually but not always duller or 
more yellowish in color, and the sheaths are commonly yellower. 
Dichothrix Bornetiana is somwehat suggestive of Harvey’s 
description and figure of Calothrix dura (Harv. Ner. Bor.-Am. 3: 
106. pl. 48 D), which Bornet and Flahault make a synonym of 
Calothrix pilosa Harv., but it has more of a Dichothrix habit, 
usually well-developed apical hairs, and no suggestion of the 
apical hemispheric cell or ‘‘ bouton,’’ which Bornet and Flahault 
have considered to be a characteristic of Calothrix pilosa. 
In addition to Polythrix corymbosa, the species is sometimes 
associated also with Scytonema crassum Naeg., as determined by 
Bornet. 
Following are three more additions to the Bahama flora: 
PORPHYRIDIUM CRUENTUM (Ag.) Nag. 
Growing sparsely on a small portion of a much cracked 
pavement, Nassau, N. P. L. J. K. Brace (comm. Feb. 17; 1920). 
LYNGBYA LUTEA (Ag.) Gomont. 
Specimens agreeing fairly well with descriptions, figures, 
and herbarium specimens of this species have been collected on 
the Berry Islands, the Exuma Chain, and Atwood (Samana) 
