380 THE AMERICAN NATURALIST. [VoL. XXXV. 
SYNOPSIS OF FAMILIES. 
CAMPANULARID&. Hydrothecze campanulate, terminal, borne on dis- 
tinct pedicels ; gonophores fixed or free-swimming.  Hydranths with large 
and somewhat trumpet-shaped hypostome. 
LAFŒIDÆ. Hydrothece deep tubular, sessile or pedicellate ; hydranths 
with conical hypostome. 
HALECIDÆ. Hydrothece usually reduced to shallow, disk-like recepta- 
cles (hydrophores). Hydranths with conical hypostome. Gonophores as 
imperfectly developed medusoids. 
SERTULARID&. Hydrothecz borne in double rows, adnate to hydro- 
caulus. Gonophores sessile. 
PLUMULARID;. Hydrothece arranged in single row only on side of 
hydrocaulus. 
CAMPANULARID&. 
Synopsis of the Genera. 
CLvTIA. Stems simple or rarely branched. Hydrothece deeply bell- 
shaped, with toothed margins, borne on long pedicels. Gonangia pro- 
ducing free meduse having four marginal tentacles. ; 
OBELIA. Stems regularly branched, hydrothecæ bell-shaped, with entire 
margins. Gonangia borne on stems and branches and producing free 
medusæ having numerous marginal tentacles. 
CAMPANULARIA. Stems simple or branched. Hydrothecæ campanu- 
late, with margins entire or variously toothed. Gonangia, medusæ as mere 
sporosacs, within which the sexual products develop and escape as rer 
planulæ. : 
GONOTHYRÆA. Stems branching ; hydrothecæ campanulate and with 
toothed margins. Gonangia producing well-developed medusoids, which, 
while often furnished with tentacles and capable of protruding beyond the 
orifice of the gonangium, never become free, thus exhibiting an interesting 
intermediate stage between the first two genera and Campanularia. 
Clytia Lamx. (in part). 
Generic characters : Stem usually simple, attached by creeping hydro- 
rhiza. Hydrothecæ devoid of operculum. Gonangia produced from stem 
or hydrorhiza and borne on pedicels which are usually beautifully annulated. 
Gonosome. Medusz deeply bell-shaped and with four marginal tentacles 
when first liberated. Otocysts eight, two in each interradius. Both these 
and the tentacles increase in number with the age of the medusa. 
