116 Proceedings of the Royal Society of Victoria. 



behind the hydrotheca. Hydrothecfe campanulate, margin entire, 

 slightly everted, rising a little above the summit of the pinna, at 

 right angles to it and the cell. Sarcothecse bithalamic, canalicu- 

 late, with slender bases, one below each hydrotheca, one on each 

 side above it, two in each axil, and one on the lower part of each 

 stem-internode. Gonothecse 7-8 times the length of the hydro- 

 thecfe, ovate, aperture terminal, rather small, somewhat oblique, 

 without internal teeth, sometimes with an elevated rim. 



Hab. — Mouth of Snowy River and Cape Lefebvre (Dr. 

 MacGillivray). 



This species is very close to P. pulchella, of which I at first 

 considered it a variety. So far as the trophosome is concerned, 

 it is distinguished by its very small size and extremely slender 

 stems, which are strongly flexuous, and bear the pinnse near the 

 summit of the internodes. In P. pidchella, on the other hand, the 

 whole structure is much more robust, the stem a good deal 

 wrinkled or annulated, with the internodes straight, very short 

 in proportion to their length, and bearing the pinnse for the 

 most part about the middle. The form and arrangement of the 

 hydrothecse and sarcothecae is the same in both species, except 

 that P. flexuosa has a sarcotheca on the lower part of each stem- 

 internode in addition to having two in each axil. The gonothecse 

 furnish the most important distinction — those of P. pulchella are 

 stout with a large aperture directed laterally, and surrounded 

 inside with large smooth teeth projecting into the interior, those 

 of P. flexuosa are much narrower in proportion to the length, 

 with a smaller aperture, only slightly oblique, and without teeth. 

 The aperture in some cases only is surrounded by an elevated 

 margin, and the general outline of the gonotheca is somewhat 

 apt to be irregular, showing at times a decided tendency towards 

 a transversely undulated form. 



Some fragments from Bondi, which I have hitherto considered 

 a dwarf variety of P. pulchella, agree with the present species 

 except in the absence of the inferior sarcotheca? of the scem- 

 internodes, a distinction not sufficiently important to forbid their 

 reference to P. flexuosa if the gonothecte should prove similar to 

 those of that species. 



