12 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



Cells with thick, swollen membranes, which merge 

 into one another and lie in a gelatinous or mucous 

 bed 3 



3. The thick membrane remains present through several 



generations, so that the cells are enclosed in several 



membranes ; cells elongated Glocothece 



Cell membranes fused into a structureless jelly in 

 which the cells are arranged without order ; cells 

 slightly longer than broad Aphanothece 



4. Cells at the periphery of spherical colonies 5 



Cells densely aggregated in spherical, elongated, or 



clathrate colonies Microcystis* 



Colonies without definite form 6 



5. Cells spherical, closely and regularly arranged around 



a hollow sphere Ccelosphoerium* 



Cells peripheric, sparsely scattered Gomphosphceria 



6. Cells enclosed in a thick membrane Gloeocapsa* 



Cells not enclosed 7 



7. Cells with thick, gelatinous, fusing membranes. . . . 



Aphanocapsa* 

 Cells single or in small groups, with membranes 

 which do not fuse Chroococcus* 



Description of Genera. 



Merismopedia Meyen. Cells spherical, or, at time of 

 division, oblong. Their regular method of division produces 

 groups of 4, 8, 16, 32, 64, or 128 cells, associated in a single 

 stratum, making a flat, freely floating, square thallus. 



M. glauca (Ehrb.) Nag., Fig. 3. 



M. convoluta Breb., Fig. 4. 



Synechococcus Nag. Cells cylindrical or oblong, found 

 singly or in series of two or more ; cell wall thin. 



Gloeothece Nag. Cells oblong or cylindrical, with 

 rounded ends. The cells divide into two nearly spherical 

 daughter-cells. The colorless gelatinous tegument may con- 

 tain one or often more cells, and this tegument may, in turn, 

 be included in a larger tegument with a family. 



