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



Asexual reproduction by 2-ciliate zoospores without red stigma 

 produced 1-4 in a cell ; also by aplanospores. 



Under the name Conferva, dating back to the time of Pliny, 

 Linnaeus included the greater part of the filamentous algae ; by 

 the steady segregation of a century and a half, it has been re- 

 duced to a small group of fresh water algae, and is here taken 

 in the extension given it by Lagerheim, 1889, p. 194. On 

 account of the impossibility of determining what plant was the 

 'type,' in the taxonomical sense, of Linnaeus, Hazen proposes 

 to drop the name Conferva entirely, substituting the Tribonema 

 of Derbes and Solier, of 1856. This seems rather too heroic 

 treatment, as all the plants included in Lagerheim's Conferva 

 have long borne that name, would certainly have been included 

 by Linnaeus under it, and cannot be placed in any other 

 accepted genus. 



KEY TO THE SPECIES OK CONFERVA. 



I. Chromatophores 2-4, symmetrically disposed. 2. C. minor. 



i. Chromatophores numerous. 2. 



2. Filaments 3-6 /it diam. i. C^bonibycina forma tennis. 



2. Filaments 6-1 1 /a diam. i. C. bombycina. 



2. Filaments 11-16 M diam. 3. C. utriculosa. 



i. C. BOMBYCINA Agardh, 1817^.78; Wolle, 1887, p. 142, 

 PI. CXXI, figs. 8 and 9; P. B.-A., Nos. 620, 1278; Tribonema 

 bombydnum Hazen, 1902, p. 184, PL XXV, figs. 1-3. Forming a 

 yellowish or whitish floccose mass ; filaments 6-n p, diam., cells 

 cylindrical or somewhat inflated, 2-4 diam. long ; cell wall thin ; 

 Chromatophores small or of moderate size, several in a cell. 

 Fig. 4. Maine to No. Carolina; Alaska to Vancouver Island ; 

 probably everywhere. Europe. 



A very common spring plant in roadside pools and brooks ; 

 the disk-shaped Chromatophores distinguish it from Microspora 

 and other filamentous algae of the same size, and the dimensions 

 separate it fairly well from other species of Conferva. 



Forma tenuis (Hazen) nov. comb.; Tribonema bombycinum 

 forma tenue Hazen, 1902, p. 185, PL XXV, figs. 4-6; Con- 

 ferva bombydna forma -minor Wille, P. B.-A., No. 621. Cells 

 3-6 /a diam., 2-12 diam. long, little if any inflated; chromato- 

 phores several, small. Greenland, Maine to N. J. Europe. 



A small, delicate, long-celled form, often found with the type ; 

 it is probably only a condition, but has quite a different appear- 

 ance. 



