G6 



THE JOURNAL OF EOTAlffY 



to be quite structureless ; and as a result of his observations he con- 

 sidered that the genus should be removed from the position near 

 Closterium, assigned to it by W. &Gr. S. West {British Desmidiacece, 

 1. 106, 1904), and placed among the. Saccoderm Desmids,. in the Tribe 



A. Fairly young vegetative cell, showing single chloroplast, lateral nucleus, and 

 end-vacuoles. B. Somewhat older vegetative cell. C, D. Fully matured 

 vegetative cells in which the chloroplast has divided in the middle into two 

 parts, and the nucleus taken up a central position. E. Two cells in con- 

 jugation, showing the extruded gametes uniting. F. Mature zygospore. 

 All XoOO. 



Spirotsenieae (near Mesotceniuni) : West {Alga;, i. 380, 1916) agreed 

 to this change. 



The chloroplast is generally single, axile, with (4?) longitudinal 

 ridges, which, however, were sometimes very indistinct, and a lateral 

 indentation in the middle where the nucleus is lodged (A, B) ; while 

 there are 4-6 p3'renoids in a central series. The chloroplast was 



