Family HYDRIDÆ.
Genus Hydra, Linné (1746).
24. H. vulgaris, Pallas (1766).
25. H. oligactis, Pallas (1766).
Naked hydrozoa which reproduce their kind by means of buds or eggs, or by fission, without exhibiting the phenomena of alternation of generations.
Family HYDRIDÆ.
Hydraidæ, Johnston, Hist. Brit. Zooph. (ed. 2) i, p. 120 (1847). Hydridæ, Hincks, Hist. Brit. Hydroid. Zooph. p. 309 (1868).
Small Eleutheroblastea in which the mouth is surrounded by hollow tentacles. Permanent colonies are not formed, but reproduction by budding commonly takes place.
Genus HYDRA, Linné.