|  Family: Trichome (filamentous structure)  with heterocysts; with equal diameter throughout hole length; 
no branching; heterocysts intervening or at base. Genus: Mucous sheath, nearly invisible; heterocysts intervening; filments solitary or agglutinate within 
a gelatinous matrix 
(Illustrations of The Japanese Fresh-water Algae, 1977).
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