162 MIDDLESEX FLORA. 



PENIUM, De Bar. 

 P. minutum, Cleve. 



P. margaritaceum, Br6b., var. punctulatum, Kalfs. 

 P. Digitus, Breb. 



CLOSTERIUM, Nitzsch. 



C. acerosum, Ehren. 

 C. costatum, Corda. 

 C. angustatum, Kuetz. 

 C. juncidum, Ralfs. 



NOSTOCACE/E. 



CALOTHRIX, Thuret. 



C. confervicola, Ag. 



Medford and Everett, on Ulva, etc., in salt water. 

 C. Crustacea, Thuret. 

 With the preceding. 



MASTIGONEMA, Kirchner. 



M. aerugineum, Kirchner. 

 Billerica, on Batrachospermum, (E. Faxon). 



RIVULARIA, Roth. 



R. radians, Thuret. 

 Spot Pond, Stoneham. 



GLOIOTRICHIA, Ag. 

 G. pisum, Thuret. 

 Medlord and Newton (W. G. Farlow). 



SCYTONEMA, Ag. 



S. ambiguum, Kuetz. 



Newton (W. G. Farlow) . 

 S. Hoffmanni, Ag. 



Newton (W. G. Farlow). 

 S. Guyanense, Mont. 



Newton, in a greenhouse, (W. G. Farlow). 



TOLTPOTHRIX, Kuetz. 



T. /Egagropila, Kuetz. 



Spot Pond, Stoneham. 

 T. truncicola, Thuret. 



Newton (W. G. Farlow). 



