Hyman, L. H. 1931b. Taxonomic studies on the Hydras of North America. IV. Description of three new species with a key to the known species. - Trans. Am. microsc. Soc. 50: 302-315, pls. 29-32
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Hyman, L. H.
1931
Taxonomic studies on the Hydras of North America. IV. Description of three new species with a key to the known species