65 i Murray* 's Northern Flora, 



first by having the leaves all under water, and of a lanceolate 

 shape, of which there are five species. The third likewise 

 contains five species, which have submersed narrow leaves, 

 mostly linear. The excellence of this plan of description 

 consists in bringing together such individuals as have 

 one common obvious characteristic ; then, in pointing 

 out their marks of distinction from kindred groups; and, 

 lastly, from each other. This will easily be appreciated by 

 the learner; and it is plain that a species will much more 

 readily be detected in a group of only three or five, than 

 among fifteen, or twenty-seven, as the case may be. The 

 ordinary definitions of genera and species contain many repe- 

 titions of characters common to similar genera of the same 

 order, and species of the same genus ; so that it is often diffi- 

 cult, especially to a beginner, to determine which is the distin- 

 guishing characteristic of a genus or species ; that is, the 

 mark whereby it may be known from its congeners and 

 kindred species. In these excellent and learned observa- 

 tions the reader will find this peculiar mark, or character, so 

 prominently exhibited, that he will have little difficulty in 

 referring any specimen to its proper species. An extract 

 from p. 90. will illustrate this : — 



" Genus II. Galium. 

 " Calyx small, 4-toothed, superior," &c. 



% " Species. 



" ^Flowers yellow. Fruit without bristles. 



" 1. Gal. cruciatura." Description. 



Locality. Four distinct places, with authorities. 

 Time of flowering. 



" 2. Gal. verum." Description. 



Locality, authority, and time of flowering, as before. 



" Obs. — These two species are separated from the succeeding members 

 of the genus by the yellow flowers and smooth fruit; while the ovate 

 hairy comparatively broad leaves, four in a whorl, sufficiently distinguish 

 G. cruciatum from G. verum." 



" #* Flowers white. Fruit without bristles." 



Gal. palustre, G. uliginosum, and G. saxatile, described as 

 before. Localities, authorities, &c. 



"Obs. — These three Galiums, like other three which immediately 

 follow them, are characterised by white flowers, and the fruit without 

 bristles. G. palustre is known by the leaves being blunt, without a bristle, 

 rather long, and sometimes unequal; G. uliginosum, by the bristle-pointed 

 leaves and rough stem ; and G. saxatile, by the granulated fruit, smooth 

 stem, and blunt though bristle-pointed leaves, which are of an ovate form, 

 and broader than in either of the others." 



G. Mollugo, pusillum, and aristatum form the next group, 

 and the subject of the succeeding observation. 



In the remarks and observations on the genera, there are 



