REPORT ON THE HYDROIDA. 
61 
Sertulciria articulata, n. sp. (PL XXIX. figs. 3, 3a). 
Trophosome. — Hydrocaulus irregularly branched, slender, divided into equal inter- 
nodes by strongly marked transverse joints, every internode carrying a hydrotheca close 
to its distal end. Hydrothecae alternate, adnate to the internodes for somewhat more 
than half their height, the free portion diverging at a high angle and very slightly tapering 
towards the orifice, which at its apocauline margin has a deep sinus bounded by two 
strong lateral cusps. 
Gonosome not present. 
Locality. — Station 149d, Royal Sound, Kerguelen Island; depth, 28 to 60 fathoms. 
The most striking character in this delicate species is found in the depth and 
distinctness of the joints, a peculiarity which gives to the hydrocaulus a decidedly 
articulated appearance, the distal end of each internode being slightly wider than the 
proximal end of the internode which rests upon it. The specimen contained in the 
collection is a mere fragment, destitute not only of gonosome but of hydrorhizal 
extremity. 
In some respects the present species approaches Sertularia johnstoni, Gray. From 
this, how r ever, which is a New Zealand species, it differs in the form of its hydrothecse, 
which in Sertularia johnstoni are slightly tumid below, as well as in their position, which 
in Sertularia johnstoni is near the middle of the internode instead of being as in the 
present species close to the distal end. 1 The jointing of the hydrocaulus, though very 
distinct in Sertularia johnstoni. does not in that species present the well-defined 
character which we meet with here as the result of the difference of diameter in the 
extremities of the two internodes where they unite to form the joint. 
Sertularia operculata, Linnseus (PI. XXX. figs. 1, la). 
Sertularia operculata , Linn., Syst. Nat. (Gmek), p. 3844. 
„ „ Lamk., Anim. sans Vert. (ed. 2), t. ii. p. 144. 
,, ,, Hineks, Brit. Hydroid Zooph., p. 263, pi. liv. 
Trophosome. — Hydrocaulus monosiphonic, slender, profusely branched, ramification 
dichotomous or subdichotomous. Hydrothecse exactly opposite, adnate to the hydro- 
caulus by somewhat more than half their height, gently curving outwards, opening 
by a very oblique orifice which occupies the greater part of the epicauline side of the 
free portion of the hydrotheca, apocauline side of orifice with a deep sinus, each of whose 
sides is produced into a strong, sharp tooth. 
Gonosome. — Gonangia elongate, oviform, tapering below to a short and narrow 
1 Journ. Linn. Soc. Lond. (Zool.), vol. xii. p. 261. 
