i 



PROF. G. DICKIE ON ALG.E OF l CHALLENGER ' EXPEDITION. 235 



which this is obtained, but, in sending to the Kew Museum an 

 additional specimen containing a characteristic bijugate leaf, 

 call attention to those already deposited by me in that Museum, 

 where not only the leaf, but the flower-bud, the flower, the 



■ 



young ovary, and stamens, identical with those of the modern 

 Trachylobium Hornemannianum are exhibited. From this w r e may 

 fairly conclude that the tree now yielding an inferior gum is 

 identical with that from which the Animi came in past ages, 

 also that the difference in the two products, which affects not 

 the market price alone, but the solubility of the gum in different 

 reagents, and quality of the varnish so made, is due not to any 

 difference in the tree or soil, or other conditions beyond age and 

 exposure in the ground, where a molecular or chemical change has 

 gone on, and a decomposition of the outer surface that makes it 

 brittle after being treated with a caustic solution, and fall off to 

 the husk, leaving the goose-skin appearance distinctive of the 

 true ground-copal. 



As I am not aware that attention has been yet called to^the 

 specimens which have been for some time exhibited in the Museum, 

 I venture, in adding one more, to annex this short memorandum. 



Contributions to the Botany of the Expedition of H.M.S. ' Chal- 

 lenger .y — Algae, chiefly Polynesian. By Professor George 

 DicKffe, M.D., F.L.S. 



[Bead April 20, 1876.] 



I. Algce collected by Mr. Moseley at Tonya tabu, from the 

 fringing reef (the rise and fall of tide about 6 feet). 



DlCTYOTACE^E. 



Pa din a Pavonia, L. 



Bhodomelace^ 



Acanthophora Thierii, Lamx. 



Laurrsciackj? 



Laurencia obtusa, Huds. 



