510 DICTYOTACEAE. 



are mostly 1-2 lines wide; and its texture is rather more rigid than in D. 

 Bartayresii. 



Dictyota linearis (Ag.) Grev. is a name that seems applicable to a very 

 narrow repeatedly dichotomous plant with segments only about one quarter of 

 a line wide that occurs attached to stones, Halimedas, etc. in shallow water, as 

 at Spanish Point. 



Dictyota dentata Lamour. [Dictyota Brongniartii J. Ag. ; D. Mertensii 

 (Mart.) Kiitz. ; D\ subdentata Kiitz.] is, like D. Bartayresii, typically a species 

 of the West Indies and northeastern South America. It has been found by 

 Mr. Collins floating in Hungry Bay (Phyc. Bor.-Am. 1926). In this species, 

 the thallus is less dichotomous and more pinnatifid than in the other Bermudian 

 species of the genus. The apices of the lobes vary from sharply acuminate to 

 obtuse. 



Dilophus guineensis (Kiitz.) J. Ag. grows near low-water mark on rocks 

 that are Avell exposed to surf action, as at Hungry Bay. The thallus is rather 

 regularly dichotomous and is commonly 1^-3 inches high with segments 4 to 1 

 line broad. In a cross section, examined microscopically, the medulla is seen to 

 consist of two layers of cells (or more in- the basal parts), while in the genus 

 Dictyota the medulla, normally at least, consists of a single layer of large 

 cells. (Phyc. Bor.-Am. 2080.) 



Sub-class RHODOPHYCEAE. 



Family BANGIACEAE. 



Bangia fuscopurpurea (Dillw.) Lyngb., which forms a soft fleece of fine 

 dark purple unbranched filaments l-l inch long on rocks and wharves between 

 the tide-lines, has been found in Harrington Sound by Dr. Hervey. 



Bangia compacta Zanard., which also occurs on rocks in Harrington Sound 

 {Howe 129), appears to differ from the foregoing in having filaments that are 

 only |-1 line long and in its cells in the uniseriate vegetative parts (except 

 base) being discoid, mostly 2-4 times as broad as long, closely compacted and 

 Lynghya-like, instead of being mostly as long as broad, as is the case in the 

 Bermuda specimens referred to B. fuscopurxiiirea. In spite of their small size 

 the filaments are often fertile and evidently mature. 



Porp]i3n:a atropurpurea (Olivi) De-Toni (Porphyra leucosticta Thuret) 

 has been reported by Collins as growing on mangroves (presumably close to the 

 low- water mark) near the Flatts Bridge and Ely's Harbor (Phyc. Bor.-Am. 

 1927 and 2085). It forms a thin oblong membranous pink thallus only one 

 cell in thickness. The species is monoecious; the antheridia form decelerate 

 patches among the darker sporocarps, both appearing first near the margins of 

 the thallus. 



Erjrthrotrichia camea (Dillw.) J. Ag. forms a commonly sparse and in- 

 conspicuous fringe of exceedingly delicate rose-colored or reddish filaments on 

 other marine algae (Polysiphonia, Hypnea, etc.) and on marine spermatophytes. 



