80 ENDEAVOUR SCIENTIFIC RESULTS. 



Genus Amphilaphis, Wright and Studer. 



Amphilaphis plumacea, Thomson and Mackinnon. 



(Plate iv.. fig. 4). 



Amphilaphis plumacea. Thomson and Mackinnon, Mem. 

 Austr. Mns.. iv., 13, 1911, p. 680, pi. Ixv., fig. 3, pi. 

 Ixviii., fig. 3, pi. Ixxiv. 



The occurrence of five colonies in this collection allows of 

 the addition of several details, especially as regards habit, 

 to the description given by Thomson and Mackinnon. 



They are slightly smaller than the 18-5 cm. high colony 

 obtained by the " Thetis " Expedition off the coast of New 

 South Wales ; the largest is 17-5 cm. in height, with a 

 diameter of 1-5 mm. at the base. One markedly flabellate 

 colony, 7-5 cm. high, has a width of as much as 13-7 cm., and 

 a diameter of 2 mm. at the base of the stem. The corres- 

 ponding dimensions of another flabellate colony are — height 

 9 cm. ; width 13-5 cm. ; diameter of stem 2 mm. 



The following significant characters can be made out. 

 The colonies are expanded in one plane. From a slightly 

 swollen base arises a cylindi'ical stem, which soon branches. 

 Lateral branches, varying much in size, are given off from 

 either side of the plane, and from these spring other branches, 

 which again divide in a dichotomous manner. 



In a few eases the coenenchyma, which is very thin, is 

 intact ; generally it is more or less worn away. The axis is 

 dark bronze in colour, and marked by fine longitudinal furrows. 



The polyps are densely crowded and arranged in a spiral. 

 They vary from 1-1-5 mm. in length. 



The dimensions of the ctenoid scales, with which the polyps 

 are armoured, are — -315 x 236 mm. ; -297 x-201 mm. ; -245 x 

 •192mm. 



The opercular scales (in the form of isosceles triangles) 

 yielded the following measurements: — -420 x-227 mm. ; -400 

 X -210 mm. ; -358 x -218 mm. 



The spicules of the coenenchyma are circular to oval scales. 

 The following measurements were taken: — -175 x- 105 mm. ; 

 •157 X- 122 mm. ; 122 x -105 mm. 



The colour of the colonies is creamy-white. 



Locality. — South-east coast of Australia. 



Distribution. — Hitherto known only from " Thetis " speci- 

 mens taken off the coast of New South AV^ales at the following 

 localities : — Eleven miles E. by N. of Barrenjoey, 30-40 

 fathoms ; Station 22, off Newcastle Bight, 40-26 fathoms ; 

 Station 40, off \\'ata Mooli, 52 fathoms ; Station 44, off 

 Coogee, 49-50 fathoms (Thomson and Mackinnon). 



