“N 
HYDROID ZOOPHYTES. 
SUB-FAMILY EUDENDRIINAE. 
EUDENDRIUM INSIGNE. 
(Plate L., fig. 4.) 
Eudendrium insigne, Hincks, British Hydroid Zoophytes (1868), pp. 86-87. 
Localities —McMurdo Bay, February 20th and 28th, 1902; March 21st, 1903; 
10-20 fathoms. 
This delicate little hydroid, consisting of small irregularly branched colonies, was 
found attached to other Coelenterata, such as Ceratoisis and Campanularia.  t did not 
occur in great abundance, but a few colonies were found in several bottles of specimens 
obtained in McMurdo Bay. 
IHydrosome——The hydrorhiza consists of a plexus of branching roots loosely 
attached to its support. At frequent intervals it gives off hydrocauli, which 
are themselves branched. These stems are very slender, strictly monosiphonie, 
seldom upright, but ‘growing in a straggling tangle like the stems of a climbing 
plant searching for a new support. The hydrorhiza and the free hydrocauli are 
invested by a thin straw-coloured perisare, which is slightly annulated at the base of 
and at intervals on the hydrocauli. 
There is considerable difficulty in distinguishing between hydrorhiza and the 
stem, and many of the stems that are now free may possibly have been at one time 
attached to the support. This difficulty renders the estimation of the height of the 
colony a matter of conjecture, but it is about 25 mm. 
The perisare frequently ends very abruptly at the base of the hydranths, 
but m some cases it seems to attenuate gradually. 
The hydranths are 0°5 mm. in height and have the usual characters of the 
genus. There are about twenty filiform tentacles 0°5 mm. in length, arranged in 
a single verticel at the base of a trumpet-shaped hypostome (fig. 4). 
At the base of the hydranth there is a circular groove bounded proximally 
by a collar of very conspicuous deeply-staining cells (fig. 4, ¢.). Occasionally 
both collar and groove are apparently absent. 
Hincks does not give a clear figure of this groove or collar in the British 
specimens, but states (p. 87) that ‘there is a circular groove near the base of the 
body, from which the gonophores spring—a portion of the structure which I 
misinterpreted at first, and which led me to suppose that there was a shallow 
cup round the base of the polypite.” From this quotation it would appear that in 
Hincks’ specimens, as in the Antarctic forms, the lower margin of the groove was 
sometimes slightly swollen out to form a collar. In general form and size the 
Antarctic specimens resemble the European specimens, but they differ from them 
in the respect that the perisare is less “closely ringed throughout.” 
