760 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, 



and the branches originate at the sides of these calycles. When 

 the soft matter is cleaned away there is usually visible a circle of 

 puncta indicating the position of the base of the hydranth, and 

 when a new calycle is formed within an old one it originates from 

 this part, which is but a short distance below the margin. The 

 base of the hydranth is usually flattened, and is united by a very 

 slender isthmus to an offshoot of the ccenosarc which occupies the 

 centre of the lower part of the hydrophore. Sometimes the 

 branches are all short, and somewhat pinnately arranged, but in 

 other specimens they are larger, occasionally equalling the stem in 

 length. 



HALECIUM PARVULUM, n.sp. 



(Plate XIV., figs 4-5). 



Hydrophyton about J to J inch high, branches ascending, stem 

 mid lower branches fascicled, stem and branches flexuous in the 

 upper portions, divided into rather short internodes by twisted 

 oblique joints, which slope alternately in opposite directions, each 

 internode bearing a calycle close to its upper extremity. Calycles 

 alternate, sub-tubular, often with other calycles springing from 

 within them ; margin expanding, strongly everted, basal part of 

 the calycle sometimes ringed. 



Gronotheca, female, large, ovate, compressed, with a large 

 concave notch at the summit, sporosac similar in outline to the 

 capsule, and nearly filling it, ova completely occupying the interior 

 of the sporosac : male, not observed. 



Hab Bondi Bay. 



In the form and arrangement of the calycles this species differs 

 little, if at all, from H. yracile, but may be distinguished from 

 that species by the compound stem and shorter internodes, as well 

 as by the difference in the gonosome. The specimens were growing 

 on a small sponge, and a very intimate union existed between the 

 sponge and the hydroid, the former having grown for some 

 distance round the basal portions of the Halecium, and the sponge- 

 fibres being closely and firmly adherent to the latter in all 



