62 
THE VOYAGE OF H.M.S. CHALLENGER. 
peduncle, summit truncated and occupied by the circular, entire orifice, which is closed 
by a chitinous lid. 
Locality . — Station 304, Port Otway, Patagonia ; lat. 46° 53' 15" S., long. 75° 12' W.; 
depth, 45 fathoms. 
I do not hesitate to refer the Hydroid here described to the Sertularia operculata, 
Linn., an abundant species of the European seas. 
The orifice of the hydrotheca extends from the apocauline wall of the divergent distal 
end almost to the point where the hydrotheca ceases to be adnate to the hydrocaulus. 
The apocauline margin of the orifice presents a deep notch or sinus, each side of which 
is produced into a sharp tooth-like lobe. This account of the hydrothecal margin 
differs somewhat from the descriptions hitherto given of this part, as seen in European 
specimens, descriptions which seem to be based on incorrect interpretation of the 
perspective under which the object usually presents itself when viewed beneath the 
microscope. 
The Challenger specimens have a height of about four inches. They were dredged off 
Patagonia from a floor of green sand, with a depth of 45 fathoms. Another station is 
thus added to the already determined wide geographical distribution of the species. 
Sertularia abietina, Linnaeus (PI. XXVII. figs. 2, 2a). 
Sertularia abietina, Lina., Syst. Nat. (GmeL), p. 3845. 
„ „ Lamk., Anim. sans Vert. (ed. 2), t. ii. p. 131. 
„ ,, Hincks, Brit. Hydroid Zooph., p. 266, pi. lv. 
Trophosome . — Main stem monosiphonic, set for nearly its entire length with pinnately 
disposed, rather close set, alternate ramuli, and often emitting branches which are similarly 
set with pinnae so as to repeat in all respects the habit of the stem from which they 
spring. Hydrothecae subalternate, two borne on each internode, adnate to the hydro- 
caulus for about one-third of their height, fiask-shaped, ventricose below, then narrowing 
into a tubular neck which diverges strongly from the internode, and terminates in an 
entire circular orifice with slightly everted margin. 
Gonosome . — Gonangia subsessile, springing from the front of the pinnae, each from a 
point close to the base of a hydrotheca, ovate, with a slightly elevated, circular and entire 
orifice. 1 
Locality . — Station 48, off Halifax, Nova Scotia ; lat. 43° 4' N., long. 64° 5' W.; depth, 
51 fathoms. 
The specimens of this Hydroid obtained by the Challenger were dredged off the 
Atlantic shores of North America. They differ in no essential point from the form as it 
1 No gonangia were present in the Challenger specimens. 
