6 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



aeriigiiions, hoinoo-eneoiis ; families of 4 with teg'ument 6-7 p 

 diam., api^roximateh^ cuboidal; tegument liomogeneoiis, hyaline. 



Growing in abundance among other species of Myxophyceae 

 on a wooden fence, at Hotel Nava, Santurce, no. 3, type, and nos. 

 2, 4a, 5, 142, and 143 a. It was also found growing on various 

 kinds of rock and walls in the following numerous localities: 

 San Juan, nos. 66 a, 92 h, 1993 a, 1999, 2004 c, 2007, 2011 and 

 2021 c; Eio Piedras, no. 177; Coamo Springs, nos. 254 a, 307 a, 

 313, 402 h, 409 h; Fajardo, nos. 682 a, 713, 717 a, 734 a, and 736 a ; 

 Palermo, no. 755 ; Laguna Tortuguero, nos. 871 and 872 ; Sabana 

 Grande, fw. 923 a; Mayagiiez, no. 982 h ; Maricao, nos. 1050, 1060 

 1061 and 1190 ; Arecibo, nos. 1337, 1363, 1368, 1372 b, 1457 and 

 1462 ; Guanica, nos. 1838 and 1841 a. 



This is an exceedingly diminutive, though distinct and well- 

 marked, species of Chroococcus. The sheath, or tegument, is 

 very thin and hyaline. P'requently only one of the cells in a 

 colony of two divides, leaviiig the colony triangular. 



Chroococcus subsphericus sp. nov. 



Plate 2, FKiURE 13 



Families composed of 2-4 cells, free among other algae, 

 spherical or subsplierical, not forming a stratum alone ; families 

 of 4, 16-19 Li diam. with the tegument ; single cells 8-10 \x diam. 

 with tegument, 6-6.5 m without tegument, purplish drab or gray ; 

 tegument hyaline, homogeneous. 



Growing among other Myxophyceae on a wall by Hot 

 Springs, Coamo Springs, no. 402 a, type, and no. 403 a. 



The above-described species seems to be nearest related to 

 C. caldariorum Hansg. There is much less variation in the size 

 of the cells, and the color is not so intense, as has been attributed 

 to that species. 



Chroococcus mediocris sp. nov. 



Plate 2, figure 14 



Families composed of 2-4 cells, free, not forming a definite 

 stratum alone; single cells spherical, bright aeruginous, finely 

 granular; families of 4 very angular, 9-11.5 p diam. without 

 tegument, 15-18 n diam. with the tegument ; tegument hyaline, 

 homogeneous, smooth. 



Growing in association with numerous other si)ecies of algae 

 in Laguna Tortuguero, no. 831 h, type. 



