408 Mr. C; C. Babiagtou on Linaria sepium. 



The law of the contrasts is therefore simpler in Monocotyledons 

 than in Dicotyledons. 



The former may be symbolized by the triangle, 3 and 6 being 

 the typical numbers in the flower ; the latter by the square or 

 pentagon, 4 and 8, 5 and 10 being the prevalent numbers. 



The simplicity of figure corresponds with simpler contrast of 

 colour in the one, while greater complexity of colour and of struc- 

 ture are in direct relation in the other. 



In families of Monocotyledons having regular flowers there is 

 regular distribution of the colours, for instance, in Amarylli- 

 dacere, Liliacere, &c. 



Orchidacese are notable examples of the other law, that irre- 

 gularity of form and of colour are associated. In a large pro- 

 portion of this family the colours are yellow or yellow-green, and 

 purple or red-purple ; the latter being confined to the part of 

 the corolla usually called lip. 



Proceeding on the principle, that since plants of all epochs of 

 the earth's history were constructed on the same general plan, 

 so the same associations of colour, and of colour and form, must 

 have prevailed also, we shall glance finally at a few conclusions 

 which may be derived from this source. 



During the earlier periods when Acrogenous Cryptogamia were 

 abundant, the secondary and tertiary colours, as russet, purple, 

 citrine, green, must have prevailed. 



During the reign of Gymnosperms, when Cycadeee and Co- 

 niferse were numerous, the secondary and tertiary colours must 

 still have given a sombre aspect to the vegetable world. 



From the commencement of the Chalk formation there appears 

 to have been a very marked and progressive increase of Angio- 

 spermous Dicotyledons, which form at least three-fourths of 

 existing vegetation. Among them we find the floral organs with 

 greater prominence in size, form and colour ; and such prominence 

 of the "nuptial dress" of the plant, to use the quaint expression 

 of Linnseus, is peculiarly a feature of species belonging to natural 

 families which have attained their maximum in man's epoch, and 

 are characteristic of it. 



XXXVII. — On Linaria sepium of Allman. 

 By Charles C. Babington, M.A., F.R.S., &c* 



At a meeting of the Royal Irish Academy, held June 6th, 

 1843, the occurrences at which arc reported in the ' Proceedings ' 

 of that body, Dr. G. J. Allman described what he supposed to 



* Read before the Edinburgh Botanical Society, Nov. Oth, 1854. 



