Proceedings. 29 



not sensibly changed the mode of grouping and separating 

 the species which was adopted by Stevens, the first serious 

 monographer of the genus, who so recently as 1822 

 described only forty-nine species then known to science. 

 The names which he then gave to some of the groups may 

 be altered, but the relative values of the characters on 

 which they are based remain without any great modifica- 

 tion, and the classification which Stevens proposed for less 

 than fifty species is found equally applicable to five or six 

 times that number. Mr. Bailey showed a set of diagrams 

 demonstrating the striking differences which exist between 

 allied European species in the size, form, colouration, and 

 sculpturing of the seeds. The life history of these plants 

 is but little known, nor is it settled whether the two 

 ubiquitous British species are annual, or perennial, or both. 

 There is little doubt, however, that they are semi-parasitic 

 in habit, living to some extent on the roots of grasses 

 and other plants, and attention was drawn to the sucker — 

 the organ by means of which they attach themselves to the 

 subterranean organs of other living plants. 



