558 
APPENDIX. [ Botany of Terra Australis. 
COMPOSITvE.* Of this family, which is the most extensive among 
Dicotyledones, upwards of 2500 species have been already described. 
About 300 are at present known in Terra Australis, in which therefore the 
proportion of Compositae to its Dicotyledonous plants is considerably smaller 
than that of the whole order to Dicotyledones generally, and scarcely half 
that which exists in the Flora of South Africa. It is also inferior in number 
of species to Leguminos®, like which it seems expedient to consider it as a 
class including several natural orders. Of these orders Cichoraceat and 
Cinarocephalce are comparatively very rare in Terra Australis, not more 
than ten species of both having hitherto been observed. 
The class therefore chiefly consists of Corymbifera ?, which are very 
generally diffused, they are however evidently less numerous within the 
tropic, and their maximum appears to exist in Van Diemen’s Island. Co- 
rymbiferae may be subdivided into sections and the greater part of the genera 
peculiar to Terra Australis belong to that section which may be named 
Gnaphaloidece, and exist either in the principal parallel or higher latitudes. 
The whole oF Composites agree in two remarkable points of structure 
in their corolla; which, taken together at least, materially assist in deter- 
mining the limits of the class. The first of these is its valvular aestivation, 
this, however, it has in common with several other families. The second 
I believe to be peculiar to the class, and hitherto unnoticed. It consists 
in the disposition of its fasciculi of vessels, or nerves ; these, which at their 
origin are generally equal in number to the divisions ol the corolla, instead 
of being placed opposite to these divisions and passing through their axes, as 
in other plants, alternate with them ; each of the vessels at the top of the 
tube dividing into two equal branches running parallel to and near the 
margins of the corresponding lacinife, within whose apices they unite. 
These, as they exist in the whole class, and are in great part of it the only 
vessels observable, may be called primary. In several genera, however, 
other vessels occur, alternating with the primary and occupying the axes of 
the laciniee : in some cases these secondary vessels, being most distinctly 
visible in the laciniae, and becoming gradually fainter as they descend the 
tube, may be regarded as recurrent ; originating from the united apices of 
* Adans, f am. 2. }>• 103. Decand. theor. elem. 216'. 
