8 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



Growing among the filaments of other Myxophyceae, princi- 

 pally Phormidium, on wood by Hot Springs, Coamo Springs, no. 

 382 a, type. 



The cells are so closely crowded in the families, and the 

 families are so close together it is difficult to state just how many 

 cells constitute a family, probably never over eight. 



Chroococcus giganteus occidentalis var. nov. 

 Plate 2, figure 17 



Single cells spherical, 32-40 m diam. without tegument, 60- 

 75 M diam. with tegument ; families of 2-A, 80-100 \x diam. with 

 tegument ; tegument hyaline, homogeneous, 11-13 p diam. 



Growing in company with other Myxophyceae in Laguna 

 Tortuguero, no. 849 h, type. 



The variety ditfers from the species in being slightly larger, 

 having a thicker tegument which is not lamellose. 



Chroococcus minutissimus sp. nov. 



Plate 2, figure 18 



Cells associated into families of 2-4, free among other algae, 

 not forming a stratum alone ; single cells with tegument 1-1.5 \x 

 diam., spherical, pale aeruginous, homogeneous; families of four 

 with tegument 4.8-5.5 n diam. ; tegument exceedingly thin, almost 

 invisible, hyaline. 



Growing upon other algae in a waterfall between Arecibo and 

 Utuado, no. 1458 b, type. 



Chroococcus minutissimus is closely related to C. cuhicus of 

 this paper. It is smaller in all of its dimensions. It is to be 

 distinguished especially by the almost complete absence of tegu- 

 ment. 



Chroococcus constrictus sp. nov. 



Plate 2, figure 19 



Families composed of 2-4 cells, adhering more or less into a 

 thin stratum, soon after division of a single free cell at times 

 becoming deeply constricted between the cells, frequently sepa- 

 rating completely before reaching the 4-celled stage; cells pale 

 aeruginous, homogeneous, spherical in the one-celled stage, 

 somewhat compressed and angular in the 2- or 4-cellod stages; 

 tegument thin, hyaline, homogeneous, firm and glutinous, single 

 cells 7.5-9 M diam. Avithout tegument. 



