SERTULARIA TUMIDA. 23 
These bands, so far as I am aware, have not been hitherto described. 
I have found them in many other Sertularidans, and they are especially 
obvious in young hydrothece. They are destitute of fibrillation, and appear 
to consist of a cord of protoplasm enclosing nucleus-like bodies, and are 
plainly intended to close the valves forming the operculum of the hydro- 
theca during the retreat of the hydranth. 
Specimens of the same variety, but in which the strong, robust habit 
was still better marked, were dredged by the “ Porcupine,” in the eastern 
parts of the North Atlantic.* 
Genus SERTULARIA Linnzvs (in part). 
Sertularia marginata. 
el QV ie igs. V2 
Trophosome. — Hydrocaulus attaining a height of about an inch, simple ; 
internodes elongated, attenuated below every pair of hydrothecw. Hydro- 
thecse opposite, deep, tubular, free, and divergent above for about three 
fifths of their height, slightly tumid below; orifice entire, with a broad rim 
formed by close stri#, which run in a circular direction round the distal 
end of the hydrotheca. 
Gonosome not known. 
Dredged from a depth of 324 fathoms, off Florida Reef. 
The species is remarkable for its distant pairs of long tubular hydro- 
thece, with the orifice surrounded by a band of delicate circular strie. 
The specimen is destitute of gonangia; it is possibly immature, and may 
become ramified before attaining its adult condition. 
Sertularia tumida. 
Pi. XVI. Figs. 3, 4. 
Trophosome. — Hydrocaulus attaining a height of } of an inch simple ; 
internodes of moderate length, thinning away for some distance below 
each pair of hydrothece. Hydrothece opposite, short, tumid below, adnate 
to the stem for about half their length, and with the distal half free and 
diverging at nearly a right angle. 
Gonosome not known. 
Tortugas, shallow water. 
* See Report of the Hydroids collected during the Expeditions of H. M. S. Porcupine, Trans. Zool. Soc. 
London, 1873. 
