162 MIDDLESEX FLORA. 



Penium, De Bar. 

 P. minutum, Cleve. 



P. margaritaceum, Br6b., var. punctulatum, Ealfs. 

 P. Digitus, Br6b. 



Clostbbium, Mtzsch. 



C. acerosum, Ehren. 

 C. costatum, Corda. 

 C. angustatum, Kuetz. 

 C. juncidum, Ralfs. 



NOSTOCACEyC. 



Calothbix, 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). 



RiVULAKIA, Eoth. 



R. radians, Thuret. 

 Spot Pond, Stoneham. 



Gloioteichia, Ag. 



G. pisum, Thuret. 

 Medford and Newton (W. G. Farlow). 



SCTTONEMA, 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). 



TOLTPOTHBIX, Kuetz. 



T. yCgagropila, Kuetz. 



Spot Pond, Stoneham. 

 T. truncicola, Thuret. 



Newton (W. G. Farlow). 



