PHYTOGRAPHIC EXPRESSIONS AND ARRANGEMENTS. 187 



Plate xiii., fig. 24.- — Exterior of valve of Trigonia margaritacea. 

 Plate xiv., fig. 25. — Outer surface of Trigonia lamarckii, seen 

 obliquely. x 300 diara. 



Plate xiv., fig. 26. — Surface of a tubercle on ribs of Trigonia 

 lamarckii, seen obliquely, showing lenses. x 600 diam. 



I take this opportunity of expressing my sincere thanks to the 

 following gentlemen for the assistance they have rendered me. 

 To Dr. H. G. A. Wright for invaluable aid in microscopy 

 with high powers and micro-photographs. To the Rev. John 

 Milne (Jurran, F.G.S., for micro-photographs and cutting many 

 sections of shells ; and for many of the latter also, my thanks 

 are due to C. S. Wilkinson, Esq., F.G.S., F.L.S. To J. Brazier, 

 Esq., C. M. Z. S., for information on the nomenclature and 

 distribution of species. To Dr. Cox and T. Whitelegge, Esq, 

 for much painstaking help which I unfortunately required from 

 the bad state of my health, and finally to Dr. Haswell of the 

 Sydney University to whom I am indebted for the use of many 

 sections of Octojms, Onchidium, and the optic tract of the common 

 house-fly. 



CONSIDERATIONS OF PHYTOGRAPHIC EXPRESSIONS 



AND ARRANGEMENTS; 

 By Baron Ferd. von Mueller, K.C.M.G., M.D., Ph.D., F.R.S- 



[Read before the Royal Society of N.S.W., October 3, 1888.'] 



The issue of a work on Victorian plants according to Lamarck's 

 clichotomous method gave rise to this treatise. It seemed desirable 

 to discuss the merits of his mode of dealing with plants for 

 descriptive purposes, more especially so, as this kind of analysis 

 has come but slightly into use during the century. Moreover the 

 opportunity appeared to be an apt one for introducing to more 

 general notice some views on the affinity and organography of 

 plants, held for a long while by the writer, but to which fullest 

 practical expressions have now only been given in the work 

 indicated. It is the " Key to the system of Victorian Plants," 

 to which is referred — the elaboration of which is just drawing to 

 its end. 



