BUTACEJE. 441 



case with all the Quassiece, Cuspariea?, and Aurantiea ; some are en- 

 tirely American, others are Asiatic and Oceanian. We have seen 

 that Diosmete is only found in South Africa, and Boroniea in Oceania. 

 ZanthoxylecR is met with in all the warm regions ; in the temperate 

 regions we only observe a few species of Zanihroxylon, Phelloden- 

 dron, which is found in North-east Asia, and Ptelea, a native of North 

 America. Suriana, a plant found near the sea, has been met with on 

 all the tropical sea-coasts. Butea? and Zygophyllea often belong to 

 cooler climates. Thus in Europe we meet with the genera Buta, 

 Dictamnus, Tribulus, ZyyophyUum, Fagonia, and Peyanum. The genus 

 Cneorum is also represented there. Only six genera are common to 

 the two Worlds \ forty properly belong to the New World. The 

 other genera belong especially to the Old, as do also all the Diosmea, 

 Boroniea, Aurantiece, Balanites, Cneorecs, and Nitrariece. The number 

 of species hitherto described, and which may be considered as dis- 

 tinct, are about nine hundred and twenty, of which only two hun- 

 dred and sixty are American; that is to say, more than two-thirds 

 belong to the Old World. 



The affinities of such a group must be many. By Zygophyllem it 

 is nearly allied to Geraniece, from which Zyyopliyllece only differ by 

 the leaves, the absence of a fragrant oil, the mode of organization 

 of the fruit, and the way in which the carpels of the Geraniece sepa- 

 rate at maturity from the central columella. The Biebersteiniece, 

 which have been really connected with the Geraniacece, are, on the 

 other hand, closely allied to Surianeae ; they only differ by their 

 entire and punctuate leaves, by the presence in each ovary of 

 Biebersteinia of a single ovule, while there are two in Suriana, where 

 they are, like the seeds, constructed in a peculiar manner. By 

 Suriana, Butacece is also closely connected with the Ochnacece, which 

 are, as we have seen, 1 scarcely separable from Quassia and Zanlhoxylece. 

 We must search much further to find a connexion between the 

 Quassias and the genus Crossosoma, which is an abnormal Banuncu- 

 lacece, (?) but having the perianth, free carpels, and bitterness of 

 Quassia, from which it only differs by its stamens, indefinite in num- 

 ber, and its arillate seeds ; it is the same with the genus Biyiostachys, 

 allied to Ochnaceae, Connaracece, Surinacece, and Bosacca, with one of 



1 Sec p. 365. 



