6 Vnivcrsity of California Puhlicatians in Botany [Vol.8 



substantiati'cl aiul more carefully studied, to constitute a reall}' decisive 

 objection. In this account the presence or absence of gonidia, together 

 with the presence or absence of certain other characteristics to be em- 

 phasized under Cluunacsiplionaceae, will be used in determining the 

 nicnibei-sliiji of each of the families of the Coccogonales. 



Key to the Gener.\. 



1. Cell division in 1 plane; plants 1-2 celled 2 



1. Ceil division in 2 planes forming a plate-like colony 3. Merismopedia (p 8) 



1. Cell divi-ion in 3 jilanos forming solid c )lonies 3 



2. Cells globular without distinct tegum3nt 1. Synechocystis (p 6) 



2. Cells longer than broad or thick, tegument present neither thick w^r strati- 

 fied '. 2: Synechococcus (p 7) 



3. Cells within the colony with distinct, often stratified teguments 4 



3. Cells within the colonj- without distinct or stratified teguments 5 



4. Colonies irregular in shape not forming a distinct thallus 



4. Chroococcus (p 9) 



4. Colonies forming a distinct, lobulated, hollow thallus 5. Placoma (p 11) 



5. Colonics free, or only slightl}' attached, cells without definite arrangement 



6. Anacystis (p 12) 



5. Colonies epiphytic or partially endophytic, cells arranged in more or less distinct 

 vertical rows 7. Chlorogloea (p 1.5) 



1. Sjmechocystis Sauvageau 



Cells spherical, free, separating soon after division, with very thin 

 walls, and blue-green protoplasts ; cell division in but one plane ; tegu- 

 ments wanting. 



Sauvageau, Sur les algues d'eau douce, 1892, p. cxv, pi. 6, fig. 2. 



The genus Synechocystis is to be distinguished hy its spherical 

 cells, elongating slightly just before division, dividing in only one 

 plane, and absolutely devoid of tegument. Its nearest relatives are 

 the species of Synechococctts. 



Synechocystis aquatilis Sauvageau 

 Plate 1, fig. 7 



Cells globose, 5-6/a diam., single or geminate, cell wall hyaline and 

 very thin ; protoplast verdigris green. 



Forming an irregular layer in pools of salt marsh. Alameda, Cali- 

 fornia. 



Sauvageau, loc. cit.; Gardner, Cyt. studies in Cyan., 1906, pp. 239, 

 268, 280, pi. 26, figs. 40-44; Collins, Holden and Setchell, Phyc. Bor.- 

 Amer. (Exsicc), no. 1206. 



