76 



MR JAMES RITCHIE : SUPPLEMENTARY REPORT ON 



Lafo'ea gracillima (Alder, 1857), var. benthophila* n. var. 



This species lias to be recorded from an additional locality, to the south of the South 

 Orkney Islands. The two specimens from this locality are, however, of a type quite 

 distinct from the Burdwood Bank examples. They are both small and incomplete. 

 The larger, 18 mm. high, bears two short branches ; the smaller, 9 mm. high, is branch- 

 less. Only a trace of fasciculation is exhibited by the latter, but the stem of the former 

 is a typical rhizocaulom. The hydrothecse, while they closely resemble those of typical 

 examples of L. gracillima, differ in being placed at more regular intervals on the stem, 

 in preserving a near approach to alternation, in lying towards the stem at a much 

 smaller angle, and in lacking a twist on the hydranthophore. 



Flo. 2. — Lafoea gracillima, var. benthophila. Portion of branch with hydrothecse. x 30. 



I do not lay much stress on this last point, however, since untwisted hydranthophores 

 are not unfrequently present in typical colonies of the species. The most striking 

 difference lies in the robustness of the hydrothecse, the dimensions being much greater 

 than in any other specimen I have examined. Near the base of the hydrotheca proper 

 is a rude row of minute, refringent prominences on the internal wall, to which the 

 base of the polyp was presumably attached. Occasionally, but only where the margin is 

 reduplicated, two rows of dots occur. 



The following table indicates in millimetres the differences, in respect of size, 

 between the present and typical specimens : — 





Coat's Land 

 Specimen. 



Burdwood Bank 

 Specimen. 



North Sea 

 Specimen. 



Eydrotheca, including hydranthophore 



,, diameter at mouth 

 Diameter of a simple tube .... 



0-87-101 



021-0-25 



016 



0-63-0-64 



0-11-0-13 



0-11 



057-0-76 

 011 



o-io 



* PevOos, the deeps ; and </>i'aos, loving. 



