Actinastrum Hantzschii var. elongatum 

Colonial and planktonic, composed of 4-16 cells not enclosed by colonial envelope. Elongatum differs from fluviatile because the cells are only narrowed toward the ends instead of sharply pointed. Average size is 4-5µ diameter and 30-35µ long with a total volume of 389.66 cubic microns. Photo on right from Back River, Baltimore. Collected June 2003.

Chlorophyceae