3o6 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



near high water mark in Norway, and in a similar station on 

 the coast of Maine. The cells are ovoid or ellipsoid, S-ioXQ-^ 

 /A, with thin wall and yellow-green contents, solitary or in a 

 formless, not very mucilaginous layer. 



27. UROCOCCUS Kiitzing, 1849, p. 206. 



Cells spherical, solitary, originally green, changing to some 

 shade of red or yellow, with large, granular, bell-shaped chro- 

 matophore and no pyrenoid ; wall thick, lamellate, the older 

 layers ultimately breaking at one side, but remaining attached 

 at the other, forming a stipe-like prolongation, of about the 

 same breadth as the cell. 



A somewhat doubtful genus, which may ultimately be ab- 

 sorbed in Gloeocystis ; it is represented in America by three 

 forms, which have been described as species, but their distinct- 

 ness is certainly open to question. 



KEY TO THE SPECIES OF UROCOCCUS. 



i. Marine. 3. U. Foslieanus. 



I. Fresh water. 2. 



2. Cells 6-15 fj. diam. i. U. Hookerianus. 



2. Cells 25-50 fj. diam. 2. U. insignis. 



1. U. HOOKERIANUS (Hass.) Kiitzing, 1849, p. 206; Wolle, 

 1887, p. 201, PI. CXXIII, fig. 13 ; Haematococcus Hookeiianus 

 Hassall, 1845, p. 325, Pi. L,XXX, fig. 4. Cells globose or 

 ellipsoid, 6-13 /A diam., blood-red when mature ; stipe densely 

 annulate, often forked. Pa. Europe. 



2. U. INSIGNIS (Hass.) Kiitzing, 1849^. 207; Wolle, 1887, 

 p. 201, PL CXXIII, figs, ii and 12; Phyk. Univ., No. 82; 

 Haematococcus insignis Hassall, 1845, p. 324, PI. L,XXX, fig. 6. 

 Cells globose, 23-53 P diam., or including thick, lamellate wall, 

 up to 70 /u, diam., brownish, orange-yellow or brick-red when 

 mature. Mass., Pa., Alaska, Vancouver. Europe. 



In early stages like a Gloeocystis, with cells 3-5 /u. diam. ; in- 

 creasing in size and number of cells, but continuing in gelati- 

 nous colonies until the cells are about io/Adiam., when they 

 become free and develop the annular wall and later the stipe. 

 The species has been studied by Richter, 1886, and it would 

 seem that the formation of the stipe does not occur until the 

 period of active vegetation is past ; for the greater part of its 

 existence the species develops as a Gloeocystis. 



3. U. FOSLIEANUS Hansgirg in Foslie, 1890, p. 156, PI. 

 Ill, figs. 4-6. Marine; cells 8-18 /* diam., green, becoming 



