HY DROIDS OF THE WOODS HOLE REGION. 
361 
Diphasia fallax (Johnston). Fig. 58. 
{Sertuiaria fallax Johnston, British Zoophytes, 8th edition, p. 127.) 
Trophosome . — Colony branched, the terminal branches often abruptly curved so as to form a hook 
or short coil. Hydrothecfe stout, with a wide, sinuous margin closed by an operculum hinged to its 
inner side. 
Gonosome . — Female gonangia with four leaf-like expansions above; male gonangia with four 
terminal spines. 
Distribution . — Shallow water, often grow- 
ing on other hydroids. A specimen found in 
the U. S. Fish Commission collection at Woods 
Hole is labeled “E. by S., Sankety, Nantucket, 
23 fathoms, V. N. E.” Off Watch Hill, 17 to 
21 fathoms. (Yerrill.) 
Diphasia rosacea (Linn.). Fig. 59. 
( Sertuiaria, rosacea Linn., Syst. Nat., 130G.) 
Trophosome . — Colony branched; branches 
more slender than in D. fallax , and more widely 
separated. Hydrothecfe delicate, transparent, 
slender, tubular, abruptly bent outward near 
the middle; aperture facing nearly upward, 
sinuous, closed with an internal operculum con- 
sisting of a single piece. 
Gonosome . — Female gonangium pyriform, 
longitudinally ridged, with two prominent 
pointed processes on top, and a round internal 
marsupium; male gonangium “pyriform, curved 
toward the base, traversed by longitudinal 
lamellated ridges, which rise abov.e into spi- 
nous processes around a slender tubular orifice.” 
(Hincks. ) 
Distribution . — Fisher Island Sound, 9 to 11 
fathoms. (Yerrill.) 
59. Diphasia rosacea 
(Linn.). 
8E RTT T L A REEL A . 
Trophosome . — Colony usually branching; stem and branches divided into regular internodes, 
each bearing one or two hydrothecae. Hydrothecfe strictly alternate, borne on opposite sides of the 
branch, usually with toothed margins provided with an operculum consisting of more than one piece. 
Gonosome . — Gonangia as in Sertuiaria, but usually more or less annulated. 
Key to species of Sertularella found in the Woods limb’ region. 
A. Hydrothecal margin without teeth or operculum S. abietina. 
A'. Hydrothecal margin with three teeth S. tricuspidata. 
A". Hydrothecal margin with 4 teeth. 
a. Teeth obscure. Hydrothecfe fusiform, deeply annulated or wrinkled transversely S. rugosa. 
a'. Hydrothecfe very large, sometimes corrugated above. Branches approximate S. gayi. 
a". Hydrothecfe medium-sized, smooth. Branches irregular and distant .8. potyzonias. 
Sertularella abietina (Linn.). Fig. 60. 
( Sertuiaria abietina Linn., Syst. Nat., p. 1307.) 
Trophosome . — Colony pinnately branched; branches thick and coarse, approximate, divided into 
internodes, each of which bears one or two hydrothecfe; nodes oblique. Hydrothecfe large, alternate, 
bulging below and narrowing above to a tubular neck with a round, even aperture without an 
operculum. 
