26 Mr. R. B. Hinds on Geographic Botany. 



altogether at variance with an opinion already expressed. The 

 world alone is their native country, and North America is as 

 much the native country of Byttneriacecs with only ten species, 

 as is Africa with eighty-eight. There is another term frequently 

 adopted, and within certain limits it is a correct one. Where the 

 greatest number of the species of a genus or family abound, 

 there is its metropolis ; but it expresses no more, and we are still 

 at a loss for a word to convey what is meant by the assemblage 

 of generic and specific characters as just mentioned. In this 

 case our ideas are best conveyed by using the adjective term of 

 the division wished to be expressed ; thus if any family has the 

 preponderance of its constituents of genera or species, or both, in 

 Europe, it would be requisite to call that family European, as to 

 this province it essentially belongs. 



Though the amount of individuals composing genera presents 

 a much smaller aggregate than is met with in the natural fami- 

 lies, still it is surprising how widely their species are diffused, 

 and how comparatively rare it is to find them bounded by nar- 

 row geographic limits. The greater portion of those genera, 

 composed of any tolerable number of species, obey the law with 

 eagerness, to reappear wherever there may be a combination of 

 circumstances propitious to their growth. To illustrate this, let 

 us take that important natural group Ranunculacece, and examine 

 how far its genera are circumscribed. Commencing with its 

 type. Ranunculus^ we shall find that it has members in all of the 

 six divisions. The same will nearly apply to Clematis and Ane- 

 mone. Very few genera are confined to a single province, perhaps 

 Knowltonia may be cited as the only one, where the number of 

 species is sufiicient to admit of a deviation ; this genus has five 

 species, all inhabitants of the Cape of Good Hope. In Crucife- 

 rm, Capparide<jef Umbelliferce, Malvacea and Caryophyllea the ge- 

 nera have a similar difinsion. Cruciferce is remarkable for con- 

 taining one extensive genus, Heliophila, of forty-seven species, all 

 from Southern Africa. 



As genera then collectively manifest so slight a disposition to 

 range within narrow limits, it will be more satisfactory to exa- 

 mine those instances in which they exist under opposite circum- 

 stances, or are comparatively circumscribed. The genera of 

 MyrtacecB are remarkable for this, and omitting those which con- 

 tain but one or two species, there are about twenty which are 

 limited to one of the divisions. Australia, always peculiar in its 

 natural productions, claims the greater share, comprising all im- 

 portant from the number of their species, and the beauty or sin- 

 gular structure of their flowers. The most prominent of these 

 are Eucalyptus, Calothamnus, Melaleuca, Metrosideros, Lepto- 

 spermum, Cahjthrix and Callistemon. A few solitary cases occur 



