PROF. THOMSON AND MR. McQUEEX REPORT ON THE ALCTONARLiNS. 



109 



t-nd, which is jihvays truncate. The stouter branches have a diameter of 

 4 mm. ; the more slender twigs of 2 mm. 



The preserved specimens have a dirty cream-colour, frequently tinged with 

 pale sulphur-yellow along one side of a branch and near the tips of the 

 twigs. In the living specimens the colour was bright light yellow, with dull 

 red joints. The specitic name I'ubrinodis has reference to the dark-red horny 

 nodes, which shine indistinctly through the whitish coenencliyma, or appear 

 as bright red patches where a branch has been broken away. 



The internodes are of very unequal lengths, varying from 7 to 32 mm. ; 

 the calcareous axis, stripped of coenencliyma, has a diameter of 1-3 mm., 

 and is white with a tinge of sulphur-yellow here and there. The longer 

 branches may have as many as seven internodes ; the shorter branches and 

 the twigs consist of only one piece. 



Fig. 1. 



Fiar. 2. 



Clathraria rubrinodis, Gray. 

 Fig. 1. Spicules. Fig. 2. Details of calcareous joints. 



On the surface of the white calcareous axis there is a characteristic sculp- 

 turins due to longitudinal furrows. There are two sets of these furrows 

 which alternate with one another. One set is deeper than the other and of 

 equal width throughout. The shallower furrows are constricted at regular 

 intervals, and the broad portions of one shallow furrow lie between the 

 constrictions of the similar furrow on either side. In these broad ovals the 

 polyps appear to be set. 



[69] 



