LIST OF iiGYPTIAN LEGUMINOS^. 53 



light is tinged yellow, the expression for the effective yellow 

 after transmission through the cylinder is 



Yr—Yqt{rm^—p^yi). 



Suppose the term in brackets to vanish, then the expression 

 for the effective yellow becomes Yr, which is independent 

 of the quantity of colouring-matter and of the length of 

 the column. 



VII. List of Leguminosm observed growing near the Egyp- 

 tian Seashore, West of Rosetta, 1875 to 1877. By 

 H. A. Hurst andA. Letourneux. 



Eead before the Microscopical and Natural-History Section, 

 April 7th, 1879. 



[Mar. indicates that the plant is said to grow in Marocco by John Ball^ 

 Esq., in his " Spicilegium Floraj Maroccana," Journal Linneau Society, 

 1878. Lx. Exs. shows that the species is represented iu the ' Plantae .ffigyp- 

 tiacae auspice A. Letourneux lectaj,' under the number given.] 



Argyrolobium uniflorum, Decaisn. Jaub. et Spach ; Lx. 

 Exs. 41 . 



Sinai; Southern Palestine; Libanotic Syria; Tunis; 

 Southern Algeria. — Boiss. 



The occurrence of this plant in Northern Egypt was, I 

 believe, first ascertained by H. H. Calvert, H.B.M. Vice- 

 Consul at Alexandria. 



Representative of a Cape genus, it is most di^cult of 



