HYDROIDA. — BALE. 29? 



Plumularia asymmetrica, Bale. 



Plumularia asymmetrica, Bale, Biological Results " Endea- 

 vour," ii., 1, 1914, p. 29, pi. iv., figs. 2-3. 



Locs. — Great Australian Bight, 130-190 fathoms, and 80-120 

 fathoms. 



Great Australian Bight, Long. 126° 45^' E., 190-320 

 fathoms. 



Plumularia procumbens, Spencer. 



Plumularia procumbens, Bale, Biological Results " Endea- 

 vour," ii., 1, 1914, p. 29 (synonymy). Id., Briggs, 

 Proc. Roy. Soc. N.S. Wales, xlviii., 1915, p. 305, pi. x., 

 fig. 1. 



Besides specimens of the usual form, several were obtained 

 which were more lax in habit, with sparser ramification, and 

 the ultimate branchlets apparently more nearly pinnate in 

 arrangement. The branches are not confined to one plane, 

 but rather straggling, and there is nothing to indicate a 

 procumbent habit. 



Spencer mentions that the primary stem, which occupies 

 the centre of the fascicle, is unjointed, having, as he surmises, 

 lost its jointing after being enveloped by the supplementary 

 tubes. In branches consisting of about a dozen tubes I 

 find the jointing of the primary one generally distinct, but 

 in a few instances it is obscure or wanting. The primary 

 tube is exactly the same in structure as the small monosiphonic 

 branchlets, any one of which may form the nucleus of a 

 polysiphonic branch. 



My former description of the ultimate branchlets as 

 springing from all sides of the larger branches is not strictly 

 accurate. Though really diverging in several directions they 

 are, in their origin, confined to the two sides, where they are 

 given off in pairs (a pair on each side alternately). As the 

 two branchlets constituting a pair diverge widely from each 

 other, they are in two planes on each side of the branch. 

 This at least is the typical arrangement, but there is much 

 irregularity, thus two pairs may follow on the same side, a 

 single branchlet may be produced instead of a pair, or one 

 may be abortive, while the amount of divergence also varies. 

 The branchlets do not spring directly from the branch, but 

 from the apophyses of the hydrocladia. These are stout and 

 bracket-like, as in P. hadia and P. cornuta, and when they 

 give origin to a pair of branchlets one of the latter springs 



