30 SYDNEY J. HICKSON anp F. H. GRAVELY. 
The type of this species was found in South Georgia, in depths of 64-250 
metres, and although the author gives no figures, we have no doubt of the identity 
oO 
of our specimens with the type. 
FAMILY EUCOPIDAE. 
GENUS OBELIA. 
Obelia geniculata. 
(Plate IV., fig. 30.) 
Sertularia geniculata, Linneeus, Syst. Nat. X. (1758), p. 812. 
Obelia geniculata, Hincks, Brit. Hyd. Zooph. (1868), p. 149, pl. xxv., fig. 1. 
Locality.—Auckland Islands, off Port Ross, March 28th, 1904. 
This very widely distributed species was found in the material obtaimed from 
the Auckland Islands. Jt has previously been described from numerous localities 
north and south of, but not within, the tropics (10: pp. 505-509; 3: p. 23; 
Apo): 
It is the only species of Hydrozoa in the collection that we have proved to 
be phanerocodonic, and it is on that account noteworthy that, notwithstanding the 
rich and varied hydroid fauna that was brought to hght by the Expedition, not a 
single specimen of this species was found under the ice in McMurdo Bay. 
A considerable number of luxuriant colonies were found growing on the frond 
of a Laminaria. 
Dimensions. 
The height of the largest colony. : . 30 mm. 
Height of hydranths . : ; » O° 4mm: 
Length of pedicels of hydranths . : . 0:25am: 
Size of gonothece . : ‘ ‘ - O°9 * 0°25 mm: 
Length of tentacles . : : ; . O°4 mm. 
The specimens differ from the common British’ type of the species in having 
two (instead of one) annular constrictions in the perisare of the hydrocaulus above 
each flexure. They also grow more luxuriantly and branch much more freely than 
the British type. 
Hydrosome.—Stem zigzag, sometimes pinnately branched, two deep constrictions 
of the perisare above each flexure. The perisare below each flexure very thick, 
forming a series of projections from which the short annulated pedicels arise. 
Hydrothecz conical, somewhat longer than they are broad, margin entire, perisare 
thick. Tentacles of the hydranth about 30 in number. Gonothece axillary, 
urn-shaped, attached by a short annulated pedicel. 
Gonosoine.-—HKach blastostyle bears numerous young scattered medusze. 
