200 HYDROIDS FROM NEW SOUTH WALES, 



Family PLUMULARID^. 



Genus Halicornaria Busk. 



Halicornaria goniodes, sp.nov. 



(Plate XXX., figs. 3-7; Plate xxxi., fig. 1.) 



Trophosome. — Hydrocaulus monosiphouie, 28 em. in height, un- 

 branched, or with a few branches near the summit. The main 

 stem gives off at irregular intervals short peduncles, which spring 

 from the front, curve upward, and fork into two branches, which 

 diverge at right angles, and have their anterior aspect directed 

 towards that of the stem. A perfect distinction is thus maintained 

 between the stem and branches. The latter reach a length of 11 

 cm., and each may give rise, midway between its point of origin 

 and its distal extremity, to a peduncle which also bifurcates into 

 two new divisions. The peduncles are divided into internodes, 

 usually eight or nine in number. They are devoid of hydroclades, 

 but are armed with a series of large sarcothecaB along their anterior 

 and posterior aspect. The stem is divided into internodes, which 

 bear two hydroclades. In the branches, the internodes fall roughly 

 into two size-groups — those on the lower part of the branch which 

 bear two hydroclades, and those on the distal part, which, as a 

 rule, bear only a single hydroclade each, and are about half the 

 length of the former. The hydroclades are alternate, 10 mm. in 

 length, both series springing from the anterior of the stem and 

 branches. They are set at an angle of about 40°, and are divided 

 into a series of internodes, each of which bears a solitary 

 hydrotheca. 



The hydrothecae are sub-cylindrical, narrowing towards the 

 base; the axis of the hydrotheca lying away from the. hydroclade 

 at an angle of about 45<*. The thickened adcauline wall of the 

 hydrotheca makes a very abrupt angle, and even in many cases is 

 prolonged past the actual base of the cell. The apocauline wall 

 meets the base at almost as sharp an angle, while the base itself 

 is straight. The margin of the hydrotheca is scalloped into seven 

 very distinct teeth, of which the median anterior one is well 

 developed and slightly recurved; while the tln^ee, wliicli occur on 



