Limitation of Genera among the Hydroida. 373 
3. LaomepzA, Lamouroux (in part). 
Trophosome.—Hydrocaulus simple or branched, rooted by a 
creeping filiform hydrorhiza; hydrothecz bell-shaped, with the 
margin entire or serrated, but without an operculum ; tentacular 
verticil surrounding the base of a very contractile, conical or 
trumpet-shaped metastome. 
Gonosome.—Gonangia developed on the hydrorhiza or hydro- 
caulus, and containing adelocodonic gonophores, which never 
leave the cavity of the gonangium. 
English authors generally include under Laomedea those species 
of Campanularide which are furnished with a branching hydrocaulus, 
while they refer to Campanularia those in which the hydrocaulus is 
simple. No generic distinction, however, can be based on this cha- 
racter—a character really unimportant, and frequently so little com- 
prehensive that we may find the two conditions combined in the 
same species, thus rendering caution necessary in the employment of 
this character, even for the purposes of specific diagnosis. 
It will be at once apparent from the diagnoses here given of Cam- 
panularia, Obelia, and Laomedea, that the differences in the gono- 
somes afford excellent characters by which we can distribute between 
three perfectly natural genera numerous forms of Campanularide 
which would otherwise defy our attempts at a satisfactory classifica- 
tion. 
* Hydrocaulus mostly branched. 
Laomedea flexuosa, Hincks (sp.), == Laomedea gelatinosa, var. a, 
Johnst. 
Laomedea neglecta, Alder. 
Laomedea angulata, Hincks. 
Laomedea amphora, Agass. 
Laomedea exigua, Sars. 
Laomedea decipiens, Wright. 
** Hydrocaulus mostly simple. 
Laomedea volubiliformis, Sars (sp.), = Campanularia volubili- 
formis, Sars. 
Laomedea poterium, Agass. (sp.), = Clytia poterium, Agass. 
Laomedea caliculata, Uincks (sp.),= Campanularia caliculata, 
Hincks. 
4, Hinexsta, Agassiz. 
Trophosome.—Hydrorhiza a creeping network of filiform 
tubes, from which a short simple hydrocaulus is emitted at in- 
tervals ; hydrothecz bell-shaped, destitute of operculum. Po- 
lypites ? 
Gonosome.—Gonangia borne on the hydrorhiza, and consist- 
ing of large, subcordate, pedunculated capsules with a small 
terminal aperture, transversely ribbed on one side, smooth on 
the other. 
