134 MINNESOTA BOTANICAL STUDIES. 



8-celled colony is produced (figure i). Although the growing plant 

 was kept under observation for several months at Lincoln, i, 2 and 

 4-celled stages were rarely found, perhaps owing to the rapid divi- 

 sion. This probably explains also why the great majority of the 

 cells seen were somewhat oblong, though a sufficient number of 

 spherical cells were found to indicate that this is the noriual shape 

 of the cell. The division of the cells is very regular and rapid, and 

 the 8-celled stage is soon followed by the i6-celled colony, and defi- 

 nite groups or families appear in the colony. In figure 2, the 16- 

 celled colony is dividing to form the 32-celled one. The next divi- 

 sion produces the 64-celled colony (figure 3), and the succeeding 

 one a 128-celled colony (figure 4 and 5). The latter divides regu- 

 larly to form the 256-celled stage. The largest colony observed was 

 cubical, and consisted of 512 cells, as shown in figure 6 and 7. The 

 colony shown in figure 6 was observed breaking up into smaller col- 

 onies, usually of 8 cells. Some of these smaller colonies broke up 

 into individual cells also. The older colonies often separate into 

 individual cells completely, but more frequently they fragment into 

 smaller colonies, which are one-half or one-fourth of the parent 

 colony. The colonies are always regular in shape and arrangement. 

 Even where a cell has died in a colony, the other cells develop nor- 

 mally. There is no other irregularity aside from unequal growth 

 in different parts of the colony. 



EuCAPSis nov. gen. 



Colonies floating, cubical, regular, when mature consisting of a 

 number of regular families, varying from 8-512 cells, usually of 

 32-128 cells; cells imbedded in a uniform gelatinous matrix, spher- 

 ical or elliptical, contents bluegreen, finely granular ; cell division in 

 three planes; propagation by fragmentation into separate cells or 

 smaller colonies; Gr. eu-, beautiful, capsis, a small box, referring 

 to the cubical colony. 



The genus is related to Chroococcus and Mcrismopcdia, from both 

 of which it differs in its symmetric cubical colony. 



Eiicapsis alpiiia n. sp. Colonies floating, very sparse. 18-80 mic. ; 

 cells in a colorless matrix, bluegreen, mostly elliptical from rapid 

 growth, or spherical, 5-7 mic. in diameter, or 6-7 x to mic. : the spe- 

 cific name refers to the apparently exclusive alpine habit. 



Colorado: In a pond at 12,000 feet on Bald Mountain; collected 



