324 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



Harvey, 1846-51, PI. XCIX.A. Filaments erect, coarse and 

 wiry, dark glaucous green, 400-500 yu, diam. ; cells 1-2 diam. 

 long. 



A common species from N. J. to Greenland, occurring also in 

 Alaska ; two forms are found ; f. RUPINCOLA (Aresch.) Kjell- 

 man, growing attached and erect, usually quite straight, in low- 

 est rock pools, and below ; reaching the length of a meter in 

 northern regions, seldom over a third of a meter on thfe New 

 England coast ; f. TYPICA Kjellman, unattached, lying loose in 

 the sublitoral zone, forming crisped and entangled masses about 

 the roots of Laminaria, etc. ; the latter form has usually been 

 known as P. Picquotiana Mont., but is now pretty generally rec- 

 ognized as a form of the present species. It seems unnatural to 

 give the name of forma typica to what is apparently a later 

 stage of the plant, but the exigencies of nomenclature require 

 it. There is considerable variation in the size of the filaments, 

 especially in f. typica, and the slender forms, sometimes as low 

 as 300 p. diam., are not always easy to distinguish from C. aerca ; 

 but the greater rigidit)^ and the dark glaucous green color are 

 usually sufficient marks. It is a favorite host for epiphytes, 

 and the number of species found growing on it in arctic regions 

 is quite large. 



3. C. ANTENNINA (Bory) Kutzing, 1849, p. 379; Vickers, 

 1908, p. 17, PL VIII; Wittr. and Nordst., Alg. Exsicc., No. 

 1439 ; C. pacifica Kiitzing, 1849, p. 379. Filaments dark green, 

 45 O -55 O P- diam., erect, somewhat flexuous, stiff below, less so 

 above; articulations 2-4 diam. long ; the lowest cell 8-50 diam. 

 long. W. I., Atlantic and Pacific coasts of Mexico. Africa. 



In habit resembling C. mclagoninni f. rupincola ; distinguished 

 by the longer cells and the very long basal cell, which tapers 

 much at the base. C. mclagonium is an Arctic species, very 

 luxuriant in Greenland, only much reduced forms being found 

 south of Cape Cod ; C. antcnnina does not appear to go farther 

 north than Cuba on the west and Morocco on the east side of 

 the Atlantic. 



4. C. AEREA (Dillw.) Kutzing, 1849, p. 379; Harvey, 1858, 

 p. 86; Farlow, 1881, p. 46; P. B.-A., Nos. 76, 1526; Conferva 

 brachyarthra Kutzing, 1845, p. 203 ; Conferva acrea Harvey, 

 1846-51, PI. XCIX.B. Filaments erect, yellowish-green, 125-400 

 ju, diam., cells about as long as broad, base of filament usually 



