MIDDLESEX FLOKA. 159 



CONJUGATVE. 



SPIROGYRA, Link. 



S. insignis, Kuetz. 



Maiden. 

 S. insignis, Kuetz., var. Hantzschii, Petit. 



With the type. 

 S. Weberi, Kuetz.? 



Maiden. No mature fruit having been found, this determination 



is not certain. 

 S. crassa, Kuetz. 



Melrose. 



ZYGNEMA, Kuetz. 



Z. stellinum, Ag. 

 Maiden and Melrose. 



P. mirabilis, A. Br. 

 Wakefield, et al. 



PLEUROCARPUS, A. Br. 



DESMIDIE/E. 



The Desmids included in this list were found by Dr. G. Lagerheim 

 attached to specimens of Utricularia, etc. , collected at Tewksbury by 

 B. D. Greene. Several of the species have not been found elsewhere. 



DESMIDIUM, Ag. 



D. aptogonum, Br6b. 



D. aptogonum, Br6b., var. acutius, Nordst. 



D. graciliceps, Lagerheim, forma major, Lagerheim. 



HYALOTHECA, Ehren. 



H. dissiliens, Br6b. 

 H. mucosa, Ehren. 



BAMBUSINA, Kuetz. 

 B. Brebissonii, Kuetz. 



SPONDYLOSITJM, Br6b. 

 S. nitens, Lund. 



SPH^EROZOSMA, Corda. 

 S. excavatum, Ralfs. 



