imi:iII /'MtlMIYTKS 21 



Gonotomt. The gonothecw (fig. 21, gth.) are immature and alxmt 0'5 x 0'4 mm. 

 in size. They are all female. They arise from the hydrocauli immediately lelow 

 the hydmthecaa and MB sessile. They are smooth, pear-shaped, and have a straight 

 margin. No gonophores can be seen, the ova being embedded in the bhwtostyles. 



This pookn is also quite distinct 



DlCTYOCLADIUM Fl'SCUM. 



(Plate III., fig. 22.) 



Locality. Cape Wadworth, Coulmau Island, January 15th, 1902; 8-15 fm. 

 Bottom stones. 



Ifytlrostmu. The single specimen of this species forms a thick, shrubby, fan- 

 shaped colony, 90 mm. in height, 80 mm. in width in the widest part, and about 

 25 mm. thick, i.e., in a direction at right auglcs to the line of greatest width and the 

 line of height. The principal branches arise irregularly from the main stem, but 

 the smaller and ultimate branches are flabellate in their mode of ramification. 

 The colony as a whole is rendered more compact than it otherwise would !> by 

 the ends of several branches developing stolons (fig. 22, #/.) which attach themselves 

 to other branches around the bases of their whorls of hydrotheca}. At the base 

 the colony is polysiphonic, but distally the branches are all monosiphonic. The 

 base and hydrorhiza arc missing. 



The hydrothecje (fig. 22, /<///.) arc arranged iu six rows and almost always in 

 regular verticels of three, but sometimes the three hydrotheca} of a verticel are not 

 quite on the same plane. They are about 0*8 mm. in length and 0*3 mm. in 

 diameter, and aduate for about one-half to two-thirds of their length. They arc 

 very slightly constricted towards the opening, the margin is quite plain and often 

 suddenly everted quite close to the edge. Reduplication of the hydrotheca} frequently 

 occurs, but the secondary thecaa project very little beyond the margin of the 

 primary ones. 



The soft parts are quite macerated. 



The general colour of the colony is pale brown. 



Gwosoine. Unknown. 



The species differs from Professor Nutting's diagnosis of the genus (19: p. 105) 

 in the absence of any operculum. In the type species of the genus (D. dic/totomum, 

 Allman ; 3 : pp. 76-77 ; PI. 36, figs. 2, 2a) the anastomosing stolons coalesce with 

 the mouths of the hydrothecae, the cavities of the hydrothecse and stolons being 

 continuous ; but in our species these stolons always grasp the hydrocauli at the ban 

 of the verticels of hydrotheca. The species differs from both D. dickvtomum of 

 Allman and D. jlitlxllutn of Nutting in the shape of the hydrotheca} and in other 

 characters. Unfortunately Allman does not mention whether an operculum is 

 present in his species or not 



