350 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Obelia liabellata (Hincks). Fig. 35. 
(Campanularia flabellata Hincks., Ann. and Mag. Nat. Hist., 3d series, vol. xvnr, p. 297.) 
Trophosome . — Colony 8 to 10 inches high, consisting of a central geniculate stem, giving forth 
branches which themselves branch in a flabellate manner; stem not fascicled, annulated above the 
origins of the branches. Pedicels borne on rather short processes or shoulders of the branches, 
distinctly annulated, short. Hydrothecse triangular in outline, margin entire. 
Gonosome . — Gonangia borne in axils of pedicels, oblong ovate, with a terminal collar and large 
round aperture. Medusae not described, so far as I can ascertain. 
Distribution . — Found in rocky tide pools (Hincks). Off Thimble Island, 4 to 5 fathoms. Woods 
Hole, in the passage (Verrill). 
Obelia commissuralis McCr. Fig. 36. 
(Proc. Elliott Soc., vol. I, No. 1, p. 197.) 
Trophosome . — Colony attaining a height of 6 to 8 inches, consisting of a central geniculate stem 
giving off branches as in 0. flabellata. Pedicels not borne on distinct shoulders of the branches, 
distinctly annulated. Hydrothecse campanulate, often subtriangular, but considerably deeper than 
in 0. flabellata. 
38. Obelia genic ulata (Linn.). 
A. Medusa. 
39. Obelia r/clatinosa (Pallas). 
A. Portion of fascicled stem (enlarged) , 
Gonosome . — Gonangia much as in the last species, but larger and less distinctly ovoid. Medusae 
at liberation with 16 marginal tentacles. 
Distribution . — Growing profusely on docks and floating timbers. Abundant all along the New 
England coast. 
The branching is exceedingly elegant and delicate, forming feathery verticillate tracery around 
the slender central stem. 
Obelia dichotoma (Linn.). Fig. 37. 
( Sertularia dichotoma Linn., Syst. Nat., p. 1312.) 
Trophosome . — Colony branching irregularly, the branches tending to assume an erect posture, 
not subverticillate. Pedicels short, usually with 4 to 6 annulations, but sometimes with many. 
Hydrothecse large, deeply campanulate, with straight sides and no teeth. 
Gonosome . — Gonangia long, slender, widening toward distal end, and terminating in a beveled 
collar. Medusae at liberation with 16 marginal tentacles. 
Distribution . — Rather shallow water. Off Gay Head, 8 to 10 fathoms. (Verrill.) 
I suspect that this is the same species as Eucope pyriformis A. Ag., but, not having seen his types, 
I can not be certain. 
