104 WISCONSIN PHYTOPLANETON 



ASTEBOCOCCUS LJMNETicus G. M. Smith. PI. 20, Figs. 7-10. 

 Trans. Wis. Acad. Sci., Arts, & Lett. 19 1 : 627, pi. 10, figs. 3-6. 1918. 



Colonies spherical, rarely ovoid, of 4-8-16 spherical cells widely 

 separated from one another and lying within a hyaline, homogeneous, 

 gelatinous matrix. Chloroplast single, star-shaped, with 4 or 8 (rarely 

 16) rays coming from a central mass and ending in a disc at the cell 

 wall. Pyrenoid single, at the center of the chloroplast. (Euplanktont). 



Diam. cells 7.5-35 /A; colonies up to 125 /* in diam. 



Chain (r),Clam (sss), Crooked (rrr), Deer (rrr), Des Moines (IT), Dummy 

 (ss), Fish (sss), Half Moon (rr), Hillman (rrr), Horseshoe (1) (ss), Horse- 

 shoe (2) (rr), Howey (rr), Lac Court Oreilles (ss), Lake of the Woods (rr), 

 Long (1) (r), Nancy (r), North Twin (rrr), Owen (cc), Reserve (r), Rooney 

 (rr), Sand (1) (r), Sand (3) (r), Shell (cc), Whitefish (sss), Wild Goose 

 (rrr). 



The shape and cellular arrangement in colonies of this species is 

 quite similar to that of Sphaerocystis, but a sharp distinction exists in 

 its star-shaped chloroplast, a type of chloroplast that is very uncommon. 

 The alga is widely distributed in the lakes of northwestern Wisconsin. 



Family DICTJOSPHAERIACEAE. 



Cells in spherical or ovoid colonies, the number in young colonies a 

 multiple of two, in older colonies indefinite. Colonies with or without 

 a gelatinous envelope. Cells held together in fours or eights by the 

 persistence of the old mother cell wall in repeatedly branching four- 

 armed thongs or irregular threads. Chloroplast single; cup-shaped, 

 or filling the entire cell ; with one pyrenoid. 



Reproduction by the division of cells into autospores which remain 

 attached to mother colony until accidentally broken away. 



KEY TO THE GENERA. 



Colony enclosed in a gelatinous sheath DICTYOSPHAERITTM 



Colony not enclosed in a gelatinous sheath. 



Cells spherical WESTELLA 



Cells ovoid to renif orm DIMOBPHOCOCCTJS 



DICTYOSPHAERIUM Nageli 1849. 



Cells spherical, ovoid, or reniform, connected with one another by 

 cruciately or dichotomously branching threads. Colony enclosed by a 

 hyaline, homogeneous, gelatinous envelope that is spherical or ovoid in 

 shape. Chloroplast single, parietal, cup-shaped, with one pyrenoid. 



