786 



vations or in certain regions, for these must of necessity be incomplete. 

 We have noticed several instances, on the Welch mountains, of plants 

 appearing in patches without much uniformity as regards elevation : 

 thus a patch of juniper commences at a great elevation on Glydir, 

 and ascends nearly to the summit ; another patch occurs fifteen hun- 

 dred feet lower down : a person descending in a direct line from the 

 summit might observe either of these patches, but not both ; and any 

 conclusion drawn from such observation must be in some degree fal- 

 lacious. Cnicus heterophyllus occurs in magnificent patches on these 

 mountains : on some mountains these patches may be a thousand feet 

 above the juniper ; on others, the juniper may have a like superiority 

 in elevation over the Cnicus. On the hills about Loch Lomond we 

 observed Polypodium Dryopteris ascending to the very summits ; in 

 Ireland the only known locality is the extreme and exposed summit 

 of Knocklayd : in Herefordshire this fern only occurs in warm shel- 

 tered woods, scarcely above the sea-level. Lycopodium Selago ap- 

 pears quite a mountain plant in North Wales ; in Sussex it rarely 

 occurs above the sea-level. From this conflicting evidence furnished 

 by plants, of local occurrence and limited range, we are not led to un- 

 dervalue the facts themselves, but we feel little disposed to deduce 

 conclusions from them. Mr. Watson is himself very circumspect in 

 drawing such conclusions, and never ventures on the expression of 

 any which can be characterized as hypothetical. 



We now arrive at a most interesting portion of Mr. Watson's work, 

 the distribution of British plants under seven different types : we need 

 make no apology to our readers for transferring the entire description 

 of these to the pages of the ' Phytologist.' 



" In addition to their distribution by provinces and climatic zones, 

 there is a third mode of indicating the geographical relations of 

 plants, which may also require some explanation. It has been be- 

 fore observed that certain species are spread over the whole island, 

 while others are limited to one, two, three or more of the provinces. 

 The same holds true in the zones; some species occurring in all of 

 them, others in one or more. Perhaps no two species have exactly 

 the same distribution or relative fi-equency ; and yet certain general 

 similarities may be traced, by which the species may be grouped to- 

 gether under a few leading Types of distribution. In the small vo- 

 lume before alluded to, by the title of ' Remarks,' certain ' geogra- 

 phic types ' were indicated (pp. 86 — 89) ; and in the ' Tabular 

 Appendix' to the same volume (115 — 184) the species were severally 

 assigned to their peculiar types. This was simply an attempt to ex- 



