﻿MR. G. BENTHAM ON THE MIMOSE^E 



347 



I 



4 



# 

 ^ 



altliougli slight, variations produced in every generation, not one, either in the parent or 

 in the adopted country, may succeed in superseding the typical form fixed through a 

 long period of unchanged circumstances. But as this typical form gains a footing in 

 new ground under new conditions, it may gradually become modified by natural selection 

 at both extremities of its thus extended area. The divergencies thus established will 

 probably, as I have on several occasions observed and specially exemplified in my Cassia 

 paper and in my Address of 1870, be in different directions in the two new countries, 

 however similar the external conditions may be in both. Two new species will be pro- 

 duced, all the more distinct if the typical form comes to disappear with the country 



Thus it is that we have representative species in distant regions 



but not derived the one from the other 



the case of 



which gave birth to it 

 having a common ori^ 



colonists. 



Returning now to the list, and keeping the above considerations in view, wo may con- 

 ceive that Acacia Sieheriam and A. Permllei may have been colonists from America of 

 very ancient date, which have become slightly modified from thoir typical forms J^a- 

 cracantha and A. lacerans, although even here we should have much doubt ; and all the 

 others suggest rather a common descent only from some typical race more or less distant 

 from both its descendants. This places them in the same category as widely dissevered 

 conveners, which we may now proceed to consider. ^ 



The following table exhibits such natural generic or subgenerio groups of Mmiose^, 

 as we find represented in both the New and the Old World m the. respechve propo. 

 tions and characteristic relations. The representative species of the la.t tahle - ^^^^^^^ 

 again included; but the few identical ones which have, as it were, lost their nat.onahty 



are passed over ; 



America. 



Oia World. 



Peittacleihra 



Paekia 



Jilamentosa 

 as above. 



as above. „ fka 



3 B^ajman ,p. of */ »me PJ-up as./^e 



World 

 Columbia, 

 subgenus. 



forming 



rather distinct 



macrop 

 above. 



1 isolated 



Asiatic and Arcblpelagi 



Entada 



PiPIADENIA 



Pbosopis 



, 1 Brazilian, with the inflorescence of 

 the San ones ; 2 with a pecohar 

 Mor^ence, extending all across tro- 

 pical America ^^^ ^^^3. 



%t:'CltZ'v.o^o^ 24 belong. 

 SI to the same section - the OM f 



(not all as yet sufficiently kaown), and 

 3 African ep. aU of a subgcnua repre- 

 sented in Araerica. 1 from the Indian 

 Archipelago, described as very different, 

 but unknown to me- None from Aus- 

 tralia nor from the Mascarene ialaadfl. 





African 



Australi 



carcne islands (except E.mimlem 



identical 

 species. 1 



African, a cticfly western 



American one a" 



East 



iligh 



ing to ine same ovw.* tmrpnre- (m uuae;, wiwi u o"»"i' «»• 



ones, 9 forming two sections unrepre- \^^^^^^^^ ,p. . i Madaga^w 



„„T,+^H m the Old VVorlcl. , • .. . .i-„ 4+u African, but ms 



V 



p., either we8tern or n?'*"^"^^ 



blown to be certuiu of its genus. None 



in Australia. . , , 



). 2 W^^'t Asiatic, scarcely tropical, 1 

 tropical African, thoie of each country 

 forming a section distinct from the 

 American ones. None in Australia az 

 the ifascarcne Ifclands, 



