BOTANY OF TERRA AUSTRALIS. 17 



have been observed, of which the greater part are referable 

 to Boronia, Correa, Eriostemon, and Zieria, of Dr. Smith, 

 and Phebalium of Ventenat. Of these genera Boronia is 

 both the most extensive and the most widely diffused, 

 existing within the tropic, and extending to the South end 

 of Van Diemen's Island ; hke the others, however, its 

 maximum is in the principal pai'allel, at both extremities of 

 which it is equally abundant. Correa, though extending 

 to the south end of Van Diemen's Island, is not found 

 within the tropic, nor was it observed at the western ex- 

 tremity of the principal parallel ; in the intermediate part 

 of which, however, where many of the peculiarities in the pig 

 vegetation of the parallel are less remarkable, or entirely 

 wanting, it may be said to abound. 



Eriostemon, which appears to be most abundant at the 

 eastern extremity of the principal parallel, has not been 

 observed either at its western extremity or intermediate 

 part ; it extends, however, to the south end of Van Diemen's 

 Island on the one hand, and within the tropic as far as 

 Endeavour River on the other. 



>L--PJiebalium, very nearly related to Eriostemon, has like 

 that genus its maximum at the eastern extremity of the 

 principal parallel, it is found also at the western extremity 

 of this parallel, and as far as the south end of A'^an Diemen's 

 Island, but it has not been observed within the tropic. 



Zieria seems to be limited to the eastern extremity of 

 the principal parallel, and the more southern regions. 



The most remarkable plant of the order with regard to 

 structure, is that imperfectly figured and described in 

 Dampier's voyage.^ Of this genus, which may be named 

 DiPLOL^NA, I have examined Dampier's original specimen 

 in the Sherardian Herbarium at Oxford, and others re- 

 cently collected, also at Shark's Bay, in the voyage of 

 Captain Baudin, and have ascertained that what appear to 

 be calyx and corolla in this singular plant, are in fact a 

 double involucrum containing many decandrous flowers, 

 whose stamina and pistilla exactly agree with those of the 



r ' Vol. 3, p. 110, tab. 3, f. 3. 



