G. M. SMITH, PHYTOPLANKTON OF ARTIFICIAL POOLS. 5 



be cliloroplast but may be lateral. When the daughter cells 

 re liberated the rupture usually occurs at a spot opposite 

 be nodule (figs. 12, 14, 15) although it may be near it (fig. 

 3). Cells were observed where there was no gelatinous 

 nvelope but usually the young daughter cells have their 

 idividual envelopes. 



'etraedron reguläre var. incus Teiling fonna. Figs, 20—25. 



Sv. Bot. Tidskr. 6: 277, fig. 12. 1912. 



The cells of this variety as found at Rydboholm almost 

 Iways have the four angles arranged pyramidately. The 

 pines at the angles are more curved than Teiling figures 

 bem, this curving of the spine giving the cell an irregular 

 utline. 



Diameter without spines 6 — 11,5 [j., with spines 18 — 25 [J.; 

 jngth of spines about 5 [x. 



Echinosphaerella limnetica G. M. Smith. Fig. 10. 



/■is. Geol. & Nat. Hist. Surv. Bull. 57, Part 1: 128, pi. 29, figs. D— 11. 1920. 



The diameter of the cells is the same as that of the 

 Iga as I have observed it in Wisconsin but the gelatinous 

 rocesses are shorter, the length of those of Swedish speci- 

 lens varying from 12 to 16 [j.. Since the closely related 

 Ichinosphaeridium Nordstedtii Lemm. is known only from 

 weden particular attention was given to the study of the 

 pines to see if there is a central seta as in Echinosphaeri- 

 ium. The gelatinous spines of the alga as found at Rydbo- 

 olm are entirely homogeneous and the distinction between 

 be two algae seems well founded. 



Lagerheimia wratislawiensis Schröder. Figs. 17—19. 



er. d. D. Bot. Ges. 15: 373, pi. 17, fig. 7. 1897; G. S. West, Jour, of Bot. 

 49: 85, fig. 2 G. 1911. 



The quadrately arranged spines were not straight in all 

 ases but some of them were undulately twisted (fig. 17). 

 'he setae also had a distinctly brownish color, especially in 



