174 THE INSTABILITY OF LEAF-MORPHOLOGY, 



L. ImigifoUa R. Br.,(?.c.;l 915, p.487), Telojyea speciosissima R.Br., 

 (I.e.; 1908, p. 286, and l.c ,1914, p. 325), and Xyloynehtm pyriforme 

 Sm.,(^.f., 1915, p. 289) [the latter also illustrating the well known 

 diversity in marginal toothing, between the juvenile and mature 

 foliage], from time to time, at the Meetings of this Society. As 

 is the case with the Urder Leguminosse, many genera of Western 

 Australian Proteaceae are exceptionally liable to variation in 

 marginal leaf-division, and dimorphism. 



THYMELEiE. 



Many specimens of Pimelea are uncertain in the alternation of 

 the leaves, and the venation is also variable. P. liiiifulia Sra., 

 an exceptionally adaptable species, and consequently wideh' dis- 

 tributed, has altered its foliar characters to meet the exigencies 

 of its varied environment. One of its forms is inseparable from 

 P. glauca R.Br., on leaf-characters. 



CASUARINEiE. 



Examples of Gasuaritia ylauca 8ieb., were exhibited ( 13; 1915, 

 p. 288) to illustrate the dislocation of the symmetry of the whorls 

 of teetll (leaves), caused by larval attack 



CONIFERiE. 



Leaf-twisting, due to mechanical injury, was demonstrated in 

 specimens of Podocarpu^ spiiitdosd R.Br, exhibited before this 

 Society (13; 1915, p. 418). This character (leaf -twisting) is occa- 

 sionally used to separate closely allied species, e.g., Conospermum 

 taxifolium Sm., v. C. ericij'olmm Sm., and Xyris comi^Ianata 

 R.Br., v. X. yracUis R.Br. In both cases cited, the character 

 is interchangeable. 



ORCHIDEiE. 



The cylindrical leaves of Dendrobium teretifolium R.Br., (ex- 

 amples of which from Tuggerah Lakes, April, 1914; Coll. A. A. 

 Hamilton, are exhibited) range from H to 18 inches long, and 

 are so similar to those of D. striolahim Reichb., that the smaller 

 plants of each species appear identical when not in flower. 



Similarity in the leafage is found in the members of the 

 opposing Orders, Iridete, and Amaryllidese, in respect of sca- 

 bridity, texture, and marginal toothing, the two former char- 



