342 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Key for identification of Campanularidx found in Woods Hole region ( based on trophosome alone). 
A. Stem neither regularly branched nor fascicled. This includes cases where a pedicel supports other pedicels springing 
from it in an irregular manner. 
a. Pedicels strongly annulated throughout. 
b. Hydrothecal margin not toothed, but entire Campanularia poterium. 
b'. Hydrothecal margin evidently toothed. 
c. Hydrothecae small, tubular. Teeth very shallow Clytia volubilis. 
c'. Teeth sharp, deeply cut. Hydrothecae small, with a tendency to irregular branching.. Campanularia minuta. 
a'. Pedicels not strongly annulated except at ends. 
b. Hydrothecal teeth squared oft' at ends. Hydrothecae ornamented with vertical lines ... Campanularia hincksii. 
b'. Hydrothecal teeth evenly rounded. Hydrothecae very large, with parallel sides and exceed- 
ingly thin walls Clytia grayi. 
b". Hydrothecal teeth sharply pointed, the extreme tips sometimes rounded. 
c. Pedicels usually more than three times the length of hydrothecae. Hydrothecae deeply 
campanulate Clytia bicophora. 
c'. Pedicels seldom more than three times the length of hydrothecae. 
d. Hydrothecae broad, often subtriangular in outline Clytia noliformis. 
d' . Hydrothecae deep, cylindrical Clytia cylindrica. 
A'. Stem regularly branched, 
a. Stem fascicled. 
b. Hydrothecae with pointed or regularly rounded teeth. Pedicels arranged in verticils around 
stem Campanularia verticillata. 
b'. Hydrothecae with very shallow, evenly rounded teeth. Colony with subverticillate branches. . Obelia longissima. 
b". Hydrothecae with square, or bimucronate teeth. 
c. Hydrothecae ornamented with vertical lines or longitudinal ridges. 
. d. Hydrothecae very deep, tubular. Pedicels with more than 6 annulations Obelia bicuspidata. 
d'. Hydrothecae not so deep. Pedicels with usually 3 to 6 annulations Obelia bidentata. 
c'. Hydrothecae without evident longitudinal lines Obelia gelatinosa. 
a'. Stem not regularly fascicled. 1 
b. Hydrothecal margin toothed. 
c. Pedicels usually in pairs or subopposite Campanularia edwardsi. 
c'. Pedicels regularly alternate. 
d. Pedicels longer than hydrothecae, not completely annulated Campanularia neglecta. 
d'. Pedicels shorter than hydrothecae. 
c. Aperture of hydrothecae broader than middle part Gonotlvyrxa tenuis. 
e' . Aperture scarcely broader than middle part Gonothyrsea loveni. 
b'. Hydrothecal margin even, not toothed. 
c. Colony with a very slender central stem from which much-branched, short, lateral branches 
arise in a verticillate manner. 
d. Hydrothecae triangular in outline. Pedicels usually with 4 to C annulations Obelia fldbellata. 
d'. Ilydrothecae deeper, subtriangular in outline. Pedicels usually with more than 6 annu- 
lations Obelia commissuralis. 
d". Hydrothecae deeply campanulate. Pedicels often considerably longer than hydrothecae 
and with their middle portions not annulated Campanularia amphora. 
c n . Colony not branched in a regularly verticillate manner. 
d. Stem nearly straight, branches strong, suberect, and giving off bushy branehlets. 
Hydrothecae very deep, campanulate. Pedicels very short Obelia dichotoma. 
d'. Stem strongly flexuose, or geniculate, usually not profusely branched, and giving off 
alternate pedicels. 
e. Stem flexuose. Hydrothecae deep, with slightly everted margins. Pedicels some- 
times quite long, with middle portions not annulated Campanularia calceolifera. 
e'. Stem decidedly flexuose, each pedicel forming a graceful curve continuous with 
the internode from which it springs. Hydrothecae campanulate. Pedi- 
cels with G to 12 annulations Campanularia flexuosa. 
e". Stem geniculate or abruptly bent at the nodes. 
/. Pedicels long, with many annulations Campanularia angulata. 
f. Pedicels short, borne on broad processes from stem. Hydrothecae subtriangular. Obelia geniculata. 
A". Colony parasitic, usually growing in a straggling or irregular manner over other hydroids. Hydrothecae 
tubular, with even margins. Pedicels very short, sometimes hardly 
apparent (Genus 1 lebella.) 
a. Hydrothecae large, curved. Colony almost always found growing symmetrically over Sertularia 
cornicina Hebella calcar ata. 
a'. Hydrothecae much smaller. Colony growing in a straggling manner over various hydroids and 
other organisms Hebella pygmxa. 
1 An appearance of fasciculation is often produced when a simple stem is overgrown with parasitic hydroids, or even 
when young colonies are growing over older ones of the same species. 
