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Genus Aciinanthes Lory. 
A. longipes. (Ag.) Apparently rare — in this county I have 
only found a few detached frustules ; in a tide pool at 
Cromer. 
A. brevipes. (Ag.) Copious in a gathering from Lynn; a few 
specimens were also found in a sand gathering from 
Hunstanton. 
Genus RrioicospnENiA Grunow. 
R corvata. (Sm.) Not unfrequent in fresh-water gatherings 
copious in a fresh-water ditch, Yarmouth. 
Family VII— CYMBELL/E. 
Genus Cymbella Agardii. 
C. Ehrenberoii. (Kiitz.) More or less frequent in all fresh- 
water gatherings. 
C. maculata. (Kiitz.) Whissonsett, Cossey, Holt, Horning ; in 
most fresh water gatherings, but not plentiful. 
Genus Cocconema Ehrenberg. 
C. lanceolatum. Ehr. Common — in most fresh-water gatherings. 
C. cisruLA. Ehr. Generally associated with the above species. 
C. cymbiforme. Ehr. Ditches, Heigham, Whissonsett, Flordon, 
Horning. 
C. parvum. (Sm.) Cossey, Flordon — rare. 
Genus Excyonema Kutztntg. 
E. prostratum. (Ralfs.) Ormesby Broad ; not common. 
E. caespitosum. Kiitz. Mixed with the preceding species. 
Genus Amphora Ehrexberg. 
A. ovalis. (Kiitz.) Copious in a ditch at Hethersett ; more or 
less frequent in all fresh-water ditches. 
A. affinis. (Kiitz.) Frequent in brackish-water gatherings. 
A. minutissima. (Sm.) Ormesby Broad. 
