168 



Calothrix scopulorum, Ag. 



Common. 

 Calothrix Crustacea, Thuret. 



Nahant (Frank S. Collins). 



Kivularia atra. Both. 

 New England (Dr. Farlow's list). 



Clathrocystis roseo-persicina, Cohn. 

 New England (Dr. Earlow's list), Gloucester (Mrs. Bray). 



ADDITIONAL SPECIES. 



Mesogloia vermieularis, Ag. 

 "Occasionally found at Cape Ann" (Dr. Farlow, in Proc. Am. 

 Acad., Vol. X), Gloucester (Mrs. A. L. Davis, in herb. P. A. S.). 



Ehizoelonium Kochianum, Kutz. 



"Lynn beach, and since found at Gloucester" (Frank S. Collins, in 



letter of Nov. 24, 1879). 

 Ehizoclonium riparium, San. 



This will be found in Essex county, as it belongs to this region. 



Monostroma pulchrum, Farlow, n. sp. 

 Nahant (Frank S. Collins). 



Note. — The fresh-veater Algse of the county have not received 

 sufficient attention from any one to make it possible to present here 

 a list even of the larger and more conspicuous species. Like the 

 Fungi, they contain immense numbers of microscopic species, many 

 of which have not been studied enough to be arranged in their proper 

 places. Among the lower forms are the Diatoms, which are also 

 found in salt water, and perhaps it is well to mention that the Proto- 

 coccus nivalis (or Red Snow of the Arctic "Voyagers) has been 

 observed at Nahant. 



