BOTANY OF TERRA AUSTRALIS. 31 



of structure in their corolla j which, taken together at least, 

 materially assist in determining 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 con- 

 sists in the disposition of its fascicuh of vessels, or nerves ; 

 these, which at their origin are generally equal in number 

 to the divisions of 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 correspond- 

 ing lacinige, 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 lacinise : in some 

 cases these secondary vessels, being most distinctly visible 

 in the lacinise, and becoming gradually fainter as they 

 descend the tube, may be regarded as recurrent ; originat- 

 ing from the united apices of the primary branches ; but [559 

 in other cases where they are equally distinct at the base of 

 the tube, this supposition cannot be admitted. A mono- 

 petalous corolla not splitting at the base is necessarily con- 

 nected with this structure, which seems also peculiarly well 

 adapted to the dense inflorescence of Coniposita3 ; the 

 vessels of the corolla and stamina being united, and so dis- 

 posed as to be least liable to suffer by pressure. 



As this disposition of vessels is found in Ambrosia and 

 Xanthium, they ought not to be separated from Compositee 

 as Richard^ has proposed ; and as it does not exist in 

 Brunonia I prefer annexing that genus to Goodenovise, 

 with which it agrees in the pecuhar indusium of the 

 stigma. 



GOODENOVI^.^ This order I have formerly separated 

 from Campanulacese, considering the peculiar membranous 

 cup surrounding the stigma, along with a certain irregu- 



i mus. 8, p. 184. = Prodi: fl. Nov. Boll. 573. 



