458 X. GENERAL REMARKS. 



divisions ; this equality of actual numbers being relatively 

 an increase in the northward direction, since the orders 

 remain equally numerous in a diminished total flora. In 

 BoraginaceiB and other instances, where some decrease is 

 seen, it is so slight as to be also a relative increase. And 

 in some few orders there is an absolute increase in the 

 number of species northward ; Amentiferce, Juncacece, 

 EricacecB, Saxifragacem, Equisetaceee, with two or three 

 smaller orders, being examples of a northerly increase. 

 NymplKeacece are among the lesser orders so appearing in 

 the list ; but if true Nuphar pumila does occur in Shrop- 

 shire and Northumberland, the three species belong alike 

 to all three latitudinal divisions. 



In very few instances does an order exhibit the largest 

 number of species in Mid Britain ; though Prirmdaceee, 

 Grossulariacece, Caprifoliace<B, Melanthiacece, and Cor- 

 nace(B appear in the list as examples of this peculiarity. 

 It is attributable to the commencement or appearance of 

 added boreal species before an equal number of southern 

 species have ceased. Grossulariace(e may or may not be 

 held such an example, according to varying views about 

 the nativity of the species of Rihes. The three succeed- 

 ing orders are increased in Mid Britain by the single 

 species, LintKea horealis, Cornus suecica, and Tofieldia 

 palustris ; which extend sparingly into that division, and 

 fail to reach South Britain. 



The number of orders unrepresented by species in the 

 three latitudinal divisions may be stated thus : — 



S. Britain, 1. Mid Britain, 4. N. Britain, 19. 

 The four orders wanting iai Mid Britain are also among 

 the nineteen absent from North Britain ; the twenty orders 

 in the whole being represented only by single genera in 

 our truly native flora, unless Araceoe, Amaryllidaceae, and 

 Hydrocharklacece are correctly to be excepted from that 



