294 CRITICAL NOTICES OF NEW PUBLICATIONS. 



the plants being found in the county or vicinity pointed out — a fact 

 which will prove exceedingly advantageous to any one investigating 

 the distribution of the species. Besides, since the Ne7v Botanuls' 

 Guide was designed to shew both the localities and the areal distri- 

 butions of all species entitled to be called Rare, with reference to 

 Britain in general, it became necessary that the author should men- 

 tion them in all the counties within which they were certainly 

 known to grow, although the}' might be common in some parlicular 

 county. The propriety and advantages of this plan are sufficiently 

 obvious, and it is equally manifest that Mr. W. has succeeded in 

 working it up to an astonishing stage of perfection. 



Although the method may not be altogether unobjectionable, 

 Mr. Watson has preferred that of selecting a certain set of species 

 according to a fixed test, and then tracing them through the whole 

 of Britain; and, with unquestionable justice, he claims for this pro- 

 cess the merit of a decided improvement, inasmuch as it affords the 

 negative evidence available to the botanical geographer. Another 

 peculiarity of his plan, is the exclusion of all the cryptogamic plants. 

 As some persons may regard this as a defect, he wishes them to bear 

 in mind that scarcely one in six of our botanical collectors feel 

 equally interested in the cryptogamian tribes as they do in the 

 others, unless it be for the ferns; but, he suggests, the defect or 

 omission can be remedied by any one who is anxious to have it done, 

 and is willing to bestow on it the requisite time and trouble. Let 

 us hope that the recommendation may be adopted. 



With regard to a line of distinction between Rare and Cotnmon 

 plants, that adopted by iVIr. Watson is sufficiently determinate; and, 

 in the present extent of our acquaintance with the intricacies and 

 anomalies of Local Botany, it appeal's clearly to be the best. He 

 I'emarks judiciously — that, between the least rare of the rarer plants 

 and the least common of the commoner plants, there can only be a 

 shade of difference, and any ado))ted test will fail of extreme preci- 

 sion ; but, in cases where the rarity or commonness of a plant is in- 

 distinguishable, it becomes a question of small moment whether it 

 be admitted or rejected, for a distinction. For the Test in his 

 guide-book, Mr. W. has adopted the comparative frequency of a 

 plant in the Local Floras he has consulted : it is the substitution of 

 the average observation of several good investigators in different 

 places, for the partial observation of one individual. As yet, the 

 local catalogues are insufficient, in number and extent, for the at- 

 tainment of complete pi-ecision ; and therefore, so long as this defi- 

 ciency remains iinsupplied, it is not too much to aver, that the New 

 Botanists' Guide will continue to afford the most faithful test for 

 the plants which it enumerates. 



Finding that he miglit be required to answer the question what 

 useful result is to ensue from such invesli<ialions into the distribution 

 of plants, Mr. Watson tenders his reply in the following instructive 

 and pertinent observations. 



