4J 



92 APPENDIX. 



single series on one side of tlie racliis_, as in S. digitaUsj 

 but are widely different in form. 



9. S. operciilata, Linn. 



Hab. — Swan Island^ Banks Strait. 



This species occurs in all parts of the world. It is to be 

 carefully distingidshed from S. bispinosa, Gray, — also an 

 Australian and New Zealand species, but which does not 

 occur in the present collection. 



b. Cells (on the branches) secmid, contiguous. 



10. S. divergens, Lamouroux. 



Cells ui'ceolate, much contracted towards the mouth ; 

 upper half free, divergent, projecting laterally almost 

 horizontally; mouth small elliptical, with the long axis 

 looking directly outwards; two lateral teeth. 0\icell 

 smooth, rounded, ovoid ; oral margin not elevated. 



Hab. — Swan Island, Banks Strait. 



Colour light yellowish : parasitic upon a fucus. Height 

 from \ to \ inch; simply pinnate, branches distant^ 

 regularly alternate. The stem is divided into internodes, 

 from each of which arises a single branch. The cells on 

 the stem are alternate. 



b. Cells secund. 



11. S. trigonostoma, n. sp. 



Cells ovoid, gibbous, much contracted towards the 

 mouth. Very small portion free, projecting forwards and 

 outwards. Mouth looking outwards and forwards, trian- 

 gular, with a short blunt tooth on the external angle. 

 Ovicell— ? 



Hab. — Prince of Wales Channel, Torres Strait, 9 

 fathoms. 



Colour very light yellowish. Polypidom simj^ly pinnate, 

 about two inches high : longest pinnae about half an inch. 

 Cells small adnate, projecting suddenly at top, and much 

 contracted at the mouth. The mouth is of a triangular 

 form, the longest side of the triangle being below. The 

 cells are placed in pairs, but one is always a little higher 



