CALKINS: SOME HYDROIDS FROM RUGET SOUND. 347 
in C. callculata , C. Integra , etc., it is much thicker than in others (cf. 
17, 9, 27, 21, etc.). Sometimes the diaphragm hears a circular 
ridge upon which the polyp rests (PI. 6, tig. 8, 9r>). Again, there 
may be a thin lamella extending inward from the thickened part, 
as Levinsen maintained (O. Integra ), in which case the diaphragm 
might he called double, and finally in still other forms the dia¬ 
phragm is exceedingly delicate and finely drawn out (PL 6, fig. 20d) . 
What real value the diaphragm has in classification remains to be 
proved. The differences presented by the Puget Sound forms cer¬ 
tainly indicate a well-defined differential, although perhaps not of 
such importance as Levinsen and Marktanner-Turneretscher assume. 
In connection with the diaphragm we must take into considera¬ 
tion the configuration of the coenosarc immediately below the 
hydranth. In nearly every case the living substance owes its 
shape to the structure of the diaphragm and basal chamber. When 
there is a space it tends to spread out, where there is a chitinous 
partition or wall it is confined. CJ. Integra (PI. 6, fig. 12 r) is 
a good illustration to the point. Here there is a well-defined basal 
chamber, also a thin partition upon which the polyp rests, and a 
thickened lower part of the* diaphragm. The coenosarc spreads 
out in the free space of the basal chamber but contracts to pass, 
through the smaller aperture of the projecting diaphragm. In 
the various forms of bases the characteristic shape of the coenosarc 
can be readily seen. It is of course not infallible; in many cases 
there may be a space without a corresponding swelling of the coe¬ 
nosarc, while in other cases a distinct tube is secreted by the coenen- 
chyme in the basal chamber (PI. 6, fig. 5e) . 
Schneider characterizes the family Campanulariidae as follows : — 
Trophosome unbranched or branched. Hydranths (at least the 
branched forms) invariably with free stalks; regularly alternate. 
Hydro theca large, with the upper part of the stalk swollen out into 
a single cup; usually conical or tubular, with or without operculum, 
and capable of taking in the entire polyp. Schneider’s genus 
Campanularia is included in the subfamily Campanuliinae which he 
characterizes as follows: — Trophosome unbranched or branched. 
Hydrotheca conical or slightly cup-formed, with distinct base invari¬ 
ably on a free stalk. Gonophores in the form of medusae or 
sporophores. Gonothecae separated. 
