1 J 4 Proceedings of the Royal Society of Victoria. 



cladia, and finally assumes a branched form. In most Plumularice 

 the primary form is pinnate, and they bear no hydrothecje on 

 the rachis ; but in species like P. campamila there is no difference 

 between the structure of pinnae and stem uncil the latter begins 

 to assume a polysiphonic form, 



Plumularia tubulosa, n. sp. 

 (Plate v., ficxs. 2-5.) 



Shoots simple, slender, about one-third of an inch in height, 

 divided by very oblique joints into rather long internodes, each 

 of which bears a hydrotheca at its lower end. Hydrotheca? set 

 at an angle of 40" to 45°, tubular, cylindrical, sometimes slightly 

 bent, twice as long as broad, and free for half their length ; 

 apertui-e plain, the sides slightly and evenly sinuated, lip curved 

 a little outwards in front. Sarcothecai bithalamic, canaliculate, 

 fixed and stout at the base, one at each side of the hydrotheca 

 (pedunculate), one in front, one midway between every two 

 hydrothecse, on the same internode as the lower. 



Gonothecse — female, large, pear-shaped, broad, somewhat flat- 

 tened above, tapering below, with a distinct sub-globular segment 

 at the base of the capsule, and a sarcotheca at each side a little 

 above the base ; a circular operculum at the summit, the border 

 of the aperture slightly thickened ; male — smaller, with one 

 .sarcotheca only. 



Almost colourless. 



^a<^.— Port Phillip Bay (Mr. J. B. Wilson). 



Closely allied to P. campanula., difiering, however, from the 

 stemless form of that species in the much greater proportionate 

 length of the hydrothecte. It is just possible that it may prove 

 to be only a variety, but so far I have failed to find any inter- 

 mediate forms, and the difference in the hydi'othecie seems to 

 fully warrant its being regarded, at least provisionally, as a 

 distinct species. Most of the Plumularians in which the hydro- 

 cladia spring direct from the hydrorhiza are known to be merely 

 stemless forms of ordinary pinnate species, and probably the 

 present species may prove no exception to the general rule ; so 

 far, however, no pinnate specimens have been observed. 



