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THE VOYAGE OF H.M.S. CHALLENGER. 
Sciurella indivisa, n. sp. (Pl. V.). 
Trophosome.—Colony attaining a height of ten inches ; stem simple, monosiphonie, 
springing in clusters from the hydrorhiza; hydrocladia closely set, about two-tenths of 
an inch in length, arranged in four longitudinal alternating series, which extend from the 
summit of the stems to within a short distance of the base. Hydrothecee deep, nearly 
cylindrical, adnate by their entire height to the supporting internode, every internode of 
the hydrocladium carrying a hydrotheca, and having, im addition to the lateral nema- 
tophores, a single mesial nematophore near its proximal end. 
Gonosome.—Gonangia in pairs from the axils of the hydrocladia, urn-shaped in front 
view, with two symmetrically placed hollow lateral processes near the distal end; 
gonangial nematophores carried by the lateral processes, by the summit of the gonangium, 
and by its sides near the base. 
As already stated (see p. 22), 1am not disposed to regard a scattered or multiserial 
disposition of the hydrocladia as affording sufficient grounds for generic separation from 
those forms of Antennularia in which the hydrocladia are verticillate. While, however, 
the disposition of the hydrocladia in Sciwrella indivisa would thus not in itself afford a 
character by which this species could be generically separated from Antennularia, such 
a character is found in the remarkable form of the gonangia, with their branching blasto- 
style and the nematophores to which their walls give support. 
The general resemblance of Sciurella indivisa to Antennularia antennina is so close, 
that, without the aid of a lens, a specimen of one of these hydroids might be easily 
mistaken for the other. The gonangium, though urn-shaped when viewed in front, is 
compressed laterally, and when viewed in profile is seen to have its axis curved backwards 
nearly in a semicircle. 
The ramification of the blastostyle in the gonangium presents considerable symmetry, 
and was similar in every instance examined. A strong branch is sent offon each side into 
the lateral projections, and each of these branches sends out three short processes and one 
long one, which all pass directly to the perforations in the walls of the gonangium, in order 
to communicate with the corresponding nematophores which le free on the outer surface of 
the walls. The short processes pass to nematophores which le near the distal end of the 
gonangium, while the long processes pass down, one on each side, to communicate with 
two nematophores situated near the base of the gonangium. 
The deep hydrothecee of Sczwrella indivisa contrast with the small shallow hydro 
thecee by which most species of Antennularia are characterised. 
Dredged off Somerset Island Cape York, Torres Strait ; 5-10 fathoms. 
