82 ' ENDEAVOUR " SCIENTIFIC RESULTS. 



PLUMARELLA FILICOIDES, Thomson and Mackinnon. 



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 2O5cm., with a width of 17-ocm. across the expanded 

 portion. Its basal attachment consists of a slightly en- 

 crusting expansion from which rises a cylindrical stem, 3mm. 

 in diameter. Branching is typically 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., with 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 bilaterally 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 twigs. The polyps are of two sizes : (1) 

 small polyps partially sunken in the ccenenchyma and closely 

 pressed against the branch. They are armed with a few- 

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

 longitudinal rows. The operculum forms a sharp, well- 

 defined cone of eight isosceles triangles ; (2) large swollen 

 polyps armed with four scales in the abaxial rows, and two 

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



The calyx scales are broad, shield-like and fan-like with 

 a distinct nucleus surrounded by numerous tuberculate 

 warts, and a narrow clear border bearing strongly marked 

 ridges -490 x -280mm. ; -367 x -350mm. ; -297 x -262mm. ; 

 262 x -525mm. The opercular scales are high, sharp- 

 pointed isosceles triangles bearing a strong T-square ridge 

 455 x -210mm. ; -385 x -192mm. ; -350 x -175mm. The 

 spicules of the coenenchyma are large, oval and fan-shaped 

 scales, without the clear border. They are covered Avith 

 tuberculate warts, which surround a well-defined nucleus 

 332 x -210mm. ; -280 x -280mm. ; -192 x- 122mm. ; -122 x 

 122mm. 



The colour of the colonies is very light brown. The axis 

 is furrowed, and of a greenish-bronze colour. 



