for the advance of Botany. 



121 



elaborating the minutest details in the history of every species it 

 contains, he cannot fail of making some observations which may as- 

 sist in approximating more closely to the discovery of the natural 

 system. Independently of any formal attempt of this kind, every 

 one who examines for himself is continually stumbling upon some- 

 thing or other, which, if it Avere recorded, would assist in refining 

 our systematic arrangements ; and such minor observations may al- 

 ways find an appropriate place in the pages of a scientific magazine, 

 when they might be considered too trifling for publication in the 

 Transactions of any scientific society. 



The greatest desideratum in scientific botany next to obtaining a 

 law for the determination of species, is some criterion for establish- 

 ing the relative values of those different groups into which species 

 are collected, under the titles of Genera, Tribes, Orders, &c, com- 

 pared with some of the best defined and most extensive natural groups, 

 such as the Compositae, Leguminosse, Gramineae, &c. There are 

 many others, considered as Natural Orders, which seem to possess 

 very slight claims to be ranked with them as groups of equal value. 

 The tendency at present appears to be more generally in favour of sub- 

 dividing those which have been previously established, than of con- 

 necting such as are most nearly allied. In the excellent publication 

 of Nees ab Esenbeck, the " Genera Plantarum Florae Germanicee," 

 this principle is carried to an extreme, and so far as it serves to point 

 out the distinct groups, however numerous, into which species may 

 be collected, nothing can be better. The next requisite is to know 

 how to distribute these minor groups into larger ones, which the au- 

 thor has also effected with great judgment. But still in the present 

 state of the science, we have no certain knowledge whether the se- 

 veral groups bearing the same name are truly of the same value. 

 The difficulty which at present attends the construction of natural 

 groups of similar value is forcibly exhibited by Mr Bentham in his 

 excellent and elaborate monograph on the Order Labiatee. Under 

 his genus Melissa, in which he includes Calamintha, Acinos, and 

 Clinopodium of other authors, he observes,* " Whether the cha- 

 racters be derived f^rom the parts of fructification or from general 

 habit, the circumscription of this and the nearly related genera of 

 Hedeoma, Micromeria, Gardoquia, and Keithia, is attended with 

 much difficulty ; and it might, perhaps, have been a clearer classi- 

 fication, if the whole had been considered as forming one extensive 

 genus, as in the case of Salvia, Hyptis, Teucrium, Szc. The relative 

 proportion, direction, and size of the upper and lower teeth of the 

 calyx, the hairs at the orifice, the proportion of the corolla to the ca- 



* P. 384, 



