17*2 ADDENDA. 



Found in Lake Jessup, five miles from Sanford, Florida. 



This species described by Delponte in his DKSMIDIACEAKIM 

 SUBAL.PINARUM is, in front view, scarcely separable from D. 

 ii/>/<>f/onum, but in lateral view it is distinct. The cells ob- 

 long elliptic, in end view not triangular. The filaments are 

 twisted, and being more than twice as wide as thick, present 

 an irregular outline, parts showing the broad front and parts 

 the narrow sides of the filaments. The margins of cells are 

 notched, and the ends excavated as in D. aptogonum. 



SPHAEROZOSMA PULCHRUM, var. CONSTRICTUM, Wolle. Plate 



XLVII, fig. 12. 



Cells half as long as wide, with a decided constriction in 

 each lobe between the axis and the apex. 

 Diameter 70-75 /*. 



Lake near Kissimme, Florida. 



GONATOZYGON SEXSPINIFERUM, Turner. Plate XLIII, fig. 15. 

 Joints variable in length, ten to thirty times the breadth ; 

 base swollen, apex either rotundo-trunca^e or quite rounded ; 

 spines, or rather setae, very short and arranged longitudi- 

 nally in six linear series. Forming long filaments. 

 Length of joints 88-180 /<; diameter 6-8 }*. 



Minnesota. 

 CL.OSTERIUM BREBISSONII, Delp. Plate VI, fig. 17. 



Cells snblinear, ends attenuated, moderately curved, apices 

 rounded ; about thirty times longer than broad ; cytioderm 

 smooth. 



Diameter 18 /A 



Observed occasionally, Minnesota and Pennsylvania. 



