82 " ENDEAVOUR " SCIENTIFIC RESULTS. 



Plumakella filicoides, Thomson and Mackimion. 



Plumarella filicoides. Thomson and Mackinnon, Mem. 

 Austr. Mus.. iv., 13, 1911, p. 686, pi. Ixv., fig. 5, pi. 

 Ixviii., fig. 1. pi. Ixxviii. 



Two specimens represent this species. One colony has 

 the basal portion intact. The larger of the two has a height 

 of 2()-5cm., with a width of 17-5cm. across the expanded 

 portion. Its basal attachment consists of a slightly en- 

 crusting expansion from Avhich rises a cylindrical stem. 3mm. 

 in diameter. Branching is tj'pically feather-like, and is 

 confined to one plane. At 5-5cm. from the base, the stem 

 gives off two stout branches which bear on each side a row 

 of alternating twigs. The stem also bears twigs, alternating 

 in a single row along each side. The twigs remain simple, 

 and their average length is 4cm., Avith a diameter of 2mm. 

 There are ten to eleven twigs on each side of a branch in a 

 length of 5cm. 



The polyps are arranged bilateralty on the stem and 

 branches ; a few, however, are scattered over the free median 

 surfaces of the latter. They are arranged in close-wound 

 spirals on the tAvigs. The polyps are of tAvo sizes : — (1) 

 small polyps partially sunken in the coenenchyma and closely 

 pressed against the branch. They are armed Avith a fcAV 

 broad scales ; there are three or four of these in the abaxial 

 longitudinal roAvs. The operculum forms a sharp, aacII- 

 defincd cone of eight isosceles triangles ; (2) large SAvollen 

 polyps armed Avith four scales in the abaxial roAvs, and tAvo 

 or three in the adaxial-laterals. The operculum is Ioav. 



The calyx scales are broad, shield-like and fan-like A\ith 

 a distinct nucleus surrounded by numerous tul^erculate 

 A\arts, and a narroAV clear l)order bearing strongly nuxrked 

 ridges— -490 x-28(;mm. ; -367 x-35()nnn. ; -297 x •262mm. ; 

 •262 X ■o25mm. The opcrciilar scales are high, sharp- 

 pointed isosceles triangles bearing a strong T-square ridge — 

 •455 X •210mm. ; ^385 x •192mm. ; •350x^r75mm. The 

 spicules of the coenenchyma are large, OA^al and fan-shaped 

 scales. Avithout the clear border. They are coA-ered Avith 

 tuberculate Avarts, A\hich surroimd a Avell-defined nucleus — 

 •332 X •210mm. ; ^280 x •280mm. ; ^192 x •122mm. ; -122 x 

 •122mm. 



The colour of the colonies is A-ery light l)rown. The axis 

 is furroAved, and of a greenish-bronze colour. 



