NEW MYXOPHYCEAE VROM PORTO RICO 



7 



The species described above has a near relative, so far as 

 size is concerned, in Chroococcus limneticns Lemm. The colonies 

 do not adhere into a stratum and the individual tegument is 

 thinner and is homogeneous, and there is no tegument investing 

 groups of cells and colonies as in C. limneticus. It is also closely 

 related to C. suhsphericus of this paper. 



Chroococcus titrgidus uniformis \ar. nov. 



Families of 4 up to 50 p diam. Avith tegument; single cells 

 with tegument 24-20 m diaiu., without tegument 13-17 m diam. 

 (up to 25 m) in the colony, bright aeruginous; tegument homo- 

 geneous, hyaline, 7-10 p thick. 



Growing among other species of algae on damp rocks, Coamo 

 Springs, no. 387 a, type. 



The variety is especially to be distinguished from the spe- 

 cies by the complete absence of lamination of the tegument and 

 by the larger size of the colonies. 



Chroococcus muralis sp. nov. 



Plate 2, figure 15 



Families composed of 2^ cells, closely aggregated, but not at 

 all coalescent ; families of four, 5-6.5 m diam. with tegument ; 

 single cells 3.5-4 [x diam. with tegument, 1.5-2 [x diam. without 

 tegument, spherical, pale aeruginous, obscured by the mem- 

 branaceous, firm, smooth, homogeneous, purplish-violet tegu- 

 ment. 



Growing on a wall, Coamo Springs, wo. 301, type. 

 The species is to be distinguished from others by the small 

 size of the cells and by the violet-colored tegument. 



Chroococcus aeruginosus sp. nov. 



Plate 2, figure 16 



Families composed of 2-4 or more cells, spread out in a thin 

 stratum among the filaments of other algae, and closely crowded 

 together ; families of four 8-10 \i diam. ; single cells spherical, 

 3.8-4.8 M diam. without tegument, bright aeruginous, homogene- 

 ous, decidedly angular in the family; tegument thin, hyaline, 

 homogeneous. 



