IV. EXPLANATIONS, ETC. 313 



of its being almost restricted to certain hilly portions of northern and 

 western England. Again, Pinguicuta vulgaris (page 305) falls into the 

 division of general species, and Par/iassia palustris (page 306) into that 

 of boreal and montane species ; and yet no great error would have been 

 committed in exchanging their places, so closely do they resemble in 

 their actual distribution. 



Austral Species. — These are subdivided into secondary groups in 

 accordance with the degree of northern latitude under which the species 

 respectively cease to be found in an indigenous state, if still found at all, 

 — or, in the case of colonists and denizens, the degree under which they 

 cease to appear as sufficiently established species: much uncertainty un- 

 avoidably attaching to this latter condition. Thus, the plants included 

 together under the head-title of " 1. Southward of 51 " will be under- 

 stood to occur somewhere or anywhere betweeu the latitudinal lines of 

 60 and 51, as traced on the map ; but they are not satisfactorily ascer- 

 tained to occur beyond the line of 51 northward. In like manner, those 

 included under the head-title of " 2. Southward of 52" must be under- 

 stood to occur somewhere between the lines of 50 and 52. So on with 

 the rest, up to the latitudinal line of 59. Those which extend also to 

 Orkney or to Shetland constitute the remaining two secondary groups of 

 the first division. 



Most of the plants placed in this division are found between the latitu- 

 dinal lines of 50 — 51, that is, quite to the south of England ; extending 

 thence in a northerly direction as far as indicated by the head-titles of 

 the several groups. Those which have not been satisfactorily ascer- 

 tained to occur between 50 — 51, are distinguished from the others by 

 having also their southern line indicated by figures set after their names, 

 that is, the line of latitude, to the northward of which they are first 

 found. Where no such indication is given, the most southerly line is to 

 be understood, that of 50. No fractions of degrees are shown ; the data 

 not having been found sufficiently complete and exact, to allow of the 

 individual species being placed in a consecutive series strictly according 

 to latitude carried out to such fractions. Thus, any plant certainly 

 known to the northward of the line of 53, however short a distance 

 above it, is entered in the group "Southward of 54." Of course, these 

 indications of latitude will not invariably correspond with those given 

 for the same species in former volumes ; more advanced knowledge 



VOL. IV. 3 S 



