899 



dred. And as, one with another, about five counties are named for 

 the north and south limits of each, we have 2,500 additional facts ; 

 which, again, will rise to 8,000 by the completion of the work. 

 These are given according to present knowledge ; but there is a pro- 

 bability, equal to a moral certainty, that several of the species will be 

 discovered in counties more northerly or more southerly than those 

 now set forth as their ascertained limits ; and where this may be the 

 case the discovery will be worth recording. It will be a fresh fact 

 added to our stores of knowledge ; and one of considerably higher 

 value than the discovery of any additional locality within the known 

 limits of the species. 



Again, in the same work, the north and south limits are also indi- 

 cated by lines of latitude. Here, then, we have another thousand 

 facts, that is, a thousand lines on the map, beyond which the species 

 are stated respectively not to be known in a truly wild state. On 

 completion of the work these will have become 3,000 reputed facts. 

 In this case, the likelihood of corrections becoming necessary is much 

 less than with the county limits. Still, it is far from improbable that 

 some of the species may hereafter be found beyond the lines indicated 

 for their latitudinal limits in Britain. Any observed fact in proof of 

 this extension must be worthy of record : it is another item to the 

 sum total of knowledge, and one which immediately admits of useful 

 application. 



The upper and lower limits of the several species are also stated, 

 so far as ascertained, both in absolute altitude and in accordance 

 with certain zones of climate and elevation (Phytol. ii. 785, 794). 

 To perfect this part of the work a vast number of additional observa- 

 tions will be required. Many of the species may yet be found higher 

 or lower than the altitudes assigned for them. And the heights to 

 which they ascend or descend on the different mountain ranges 

 should also be ascertained and compared in order to afford the ne- 

 cessary data for determining the influence of latitude, and numerous 

 more local conditions, in elevating or depressing the limits of the 

 species. As the matter now stands, the first volume of the Cybele 

 may be said to give 2,000 facts under the head of altitude ; and these 

 will become 6,000 in the entire work. 



Besides the preceding points, there are the types of distribution ; 

 the ranges of mean annual temperature ; occasional enumeration of 

 counties or localities for the rarer species ; their usual situations of 

 growth ; their claims to be ranked as natives or otherwise ; their es- 

 timated census, with various queries and suggestions; including toge- 



