330 M. C. Mereschkowsky on the Hydroida. 
but frequently individuals are met with in which this part 
diminishes very little, and thus acquires a nearly cylindrical 
form (Pl. XIV. fig. 2,a). Another characteristic feature is the 
shortness of the pedicels which support the hydrothece, and 
which are a little less than half the length of the hydrotheca, 
whilst in Z. tenuzs the pedicel is longer than the hydrotheca. 
The annulation is pretty well marked, but far from attaining 
the development observed in Campanulina repens, which is 
further distinguished from Leptoscyphus Grigoriewi by the 
mode of ramification and the form of the hydrotheca. In our 
species the annulation is clearly marked only in the pedicels, 
and on the branches above the points of insertion of the latter. 
The colour of the branches is especially distinct at the base of 
the colony, where it is a dull brown; it becomes lighter and 
lighter towards the middle, and finally disappears at the ex- 
tremity. The hydrothece are always colourless. 
Length of the hydrothece (average) 0°34 millim., length 
of the superior cone 0:1, maximum breadth of the hydrotheca 
0091, length of the pedicel 0°15, breadth of the branches 
0-065. 
Sertularella gigantea, mihi. (Pl. XIV. figs. 6, 7.) 
Sertularia polyzonias, Linn., var. robusta, Sars, “ Bidrag til Kundskaben 
om Middelhavets Litoral-Fauna,” in Nyt Magazin for Naturvidens- 
kaberna, 1857, p. 163. 
Sertularia polyzonias, Linn., polyzonias (ex parte), Hincks, Hist. Brit 
Hydr. i. p. 235. 
Sertularia polyzonias, Linn., var. gigantea, Hincks, “ On Deep-water 
Hydroida from Iceland,” Ann. & Mag. Nat. Hist. ser. 4, vol. xiii. 
(1874), p. 151, pl. vii. figs. 11, 12. 
Sertularta polyzonias, Linn., var. gigantea, Hincks, 8. Smith and O. 
Hagen, “ Report on the Dredgings in the Region of St. George's 
Banks in 1872,” Trans. Conn. Acad. of Arts and Sciences, iii. part i. 
(1876), p. 53. 
The tolerably flexible stems spring from the branched hydro- 
rhiza often without ramifying ; sometimes they divide at their 
base into two or three branches, each of which may again 
ramify once more; the terminal branches are in all cases very 
long and straight. The hydrothece are evidently alternately 
arranged upon the angularly bent stem; frequently we ob- 
serve three or four undulations (ribs) crossing the hydrotheca ; 
its form is much elongated, only a little widened at its base ; 
in size it is two or three times the length of the hydrotheca of 
S. polyzonias. In adult individuals the margins are always 
furnished with several ledges, and an equal number of small 
opercula placed one above the other. Below each hydrotheca 
the stem 1s slightly ringed. 
Gonophores unknown. 
