HYDROIDS OF THE WOODS HOLE REGION. 
341 
HYBOCONIDAE. 
Trophosome . — Colony unbranched. Stem with a distinct chitinous perisarc, and rooted to a true 
hydrorhiza. Hydranths large, with a proximal and distal set of filiform tentacles. 
Gonosome . — Gonophores producing free medusae. 
HYBOCODON. 
Trophosome . — Stem with distinct, deeply annulated expansion just below hydranth. Hydranth 
with a proximal whorl and two distinct but closely approximated distal whorls of filiform tentacles. 
Gonosome . — Gonophores attached directly to the hydranth body without the intervention of 
peduncles and developing into free medusae, each of which has a single large tentacle bearing succeed- 
ing generations of medusae. The medusa are deeply campanulate, with 4 radial canals and a short 
proboscis. 
Hybocodon prolifer Ag. Fig. 76. 
(Cont. Nat. Hist. U. S., iv, p. 243.) 
Trophosome . — Hydrocaulus unbranched, longitudinally striped owing to the coonosarcal canals 
showing through; perisarc suddenly enlarging near the hydranth, where a number of collar-like 
swollen rings appear, the uppermost being the largest. Hydranth much like that of Tubularia, but 
with two distinctly separated whorls of tentacles around the proboscis, each whorl being composed of 
about 16 tentacles, the lower being twice as long as the upper. 
Gonosome . — Gonophores adnate to the hydranth body just above the basal whorl of tentacles, 
producing free medusae with four radial canals and five superficial meridional orange-colored bands 
when fully mature. The single tentacle is greatly enlarged and near its base a number of medusae in 
various stages of development are attached, and these again may in the same manner bear still other 
groups of medusae. 
Color . — The pigmentation of both hydranth and medusa is orange red. 
Distribution . — Deep pools of sea water (Agassiz). The medusa only has been taken at Woods 
Hole, being collected in the tow net by Mr. Vinal Edwards on March 2. At that time the orange 
bands were not conspicuous. 
Suborder CALYPTEROBLASTEA. 
Hydrothecae and gonangia present. 
CAMPANULARID/E. 
Trophosome . — Ilydrothecae well developed, nonoperculate, either with distinct pedicels or nearly 
sessile, but not adnate to or partly immersed in stem or branches. Hydrothecal cavity distinctly 
differentiated from cavity of stem by a septum perforated to allow a ccenosarcal connection between 
hydranth and pedicel. Hydranth with a trumpet-shaped or subglobular proboscis. 
Gonosome . — Gonophores either developing the generative products directly or producing medusae 
which usually have otocysts and in which the ovaries are situated along the course of the radial 
canals and sometimes on the proboscis also, but never on the proboscis alone. 
Key to genera of Campanularidse found in the Woods Hole region. 
A. Stem not regularly branched. 
a. Hydrothecae on long pedicels. 
b. Free medusae with four marginal tentacles at birth Clytia. 
b'. No medusae. Reproduction by planulae Campanularia. 
a'. Hydrot.hecae tubular. Pedicels short. Margin of hydrothecae entire, not toothed Hebella. 
A'. Stem regularly branched. 
a. Free medusae with 16 or more marginal tentacles. I.ithocysts on the bases of tentacles Obclia. 
a'. No free medusae, the mature gonangia bearing medusa-like bodies on their summits Gonothyrsea. 
a". No free medusae, the planulae being developed within the gonangium Campanularia. 
The Campanularidse offer great difficulties in identification, owing to the necessity of basing generic 
characters on the gonosome and the practical identity of the trophosomes of different genera. The 
following entirely artificial key, although inadequate in some cases, is presented to aid the collector 
and student in the identification of specimens without the gonosome. 
