Chrysophyta which lacks a pyrenoid and has a parietal, plate-like 

 chloroplast along the lateral walls. There are species in that genus 

 which are similar in shape and habit to Stylosphaeridium, but they 

 are usually much larger. 



Stylosphaeridium stipitatiim ( Bachm. ) Geitler & Gimesi 

 in Geitler 1925, p. 608 



PI. 4, Figs. 7-9 



Characteristics as described for the genus. Cells 5-8/i, in diameter, 

 8-lOju, long; stipe 20fi long. 



This species apparently is not widely distributed in lakes of our 

 region, but in the habitats where it does occur it is common. The 

 plants are gregarious, and the host colony is usually thickly beset 

 with the epiphytes. Mich., Wis. 



FAMILY COCCOMYXACEAE 



Plants in this family are ovate, ellipsoidal, cylindrical or fusiform 

 cells, either solitary or forming colonies inclosed by a copious muci- 

 laginous investment. There is a single parietal chloroplast which 

 may have a pyrenoid. 



The genera of the Coccomyxaceae are not altogether typical of 

 the Tetrasporales but are precluded from possible classification with 

 the Chlorococcales by the fact that the cells can undergo cell division 

 in the vegetative state. 



Key to the Genera^ 



Cells fusiform or elongate-cylindric, arranged in a copious 



mucilage to form spindle-shaped colonies Elakatothrix 



Cells ovate or oblong, arranged in a flat plate 



within a rectangular gelatinous sheath— Dispora 



DISPORA Printz 1914, p. 32 



Cells ovate to oblong, sometimes nearly spherical; pairs or quar- 

 tets of cells irregularly arranged within a wide gelatinous sheath, 

 forming a flat, rectangular plate, the colony increasing in size by cell 

 division in 2 directions in the same plane; chloroplast a parietal cup, 

 without a pyrenoid ( ?) . 



Dispora has been placed by Printz in another family, the Pleuro- 

 coccaceae, together with Coccomyxa, Psetidotetraspora, and Elakato- 

 thrix. Fritsch (1935) suggests that a suitable place for Dispora 

 would be with the Palmellaceae. 



-Since this key was written, Coccomyxa dispar Schmidle has been collected in a Michigan 

 lake. This consists of ellipsoidal cells embedded in amor^^hous mucile /e. 



[92] 



