240 ANNALS OF SCOTTISH NATURAL HISTORY 



forma super- canescens, Kiik. = C. tetrastachya, Traunst. = C. 

 helvola, Druce, var. In my " List," which was published 

 before I saw the " Monograph," it appears as echinata x 

 canescens C. tetrastachya, Traunst At the time we 

 gathered it C. echinata was still flowering; C. canescens, as 

 its var., was much over. 



The locality has since been visited by two or three 

 botanists ; but the plant sent to me by them has been 

 C. canescens, L., var. robustior, Anders., which I saw some- 

 what higher up on the hill, but in the same drainage area. 

 Therefore if C. echinata is crossed with canescens it would 

 be rather with the var. robustior, which is in the locality, 

 than with var. fallax, which is not recorded for that vicinity. 

 But the point is this : the small plateau on which C. helvola 

 grew yielded one year plants which Kukenthal named, with- 

 out doubt, C. Jielvola ; another year the same place also 

 yielded some doubtfully referred to canescens x echinata. In 

 the following year plants nearer canescens were obtained, and 

 I saw canescens, var. robustior, too there. Since then I am 

 told the var. robustior has alone been noticed. 



Can it be that a plant at first distinguished as helvola 

 has been recrossed with one of its parents until the prepotent 

 form has subjugated the weaker ? 



Such a case happened at Oxford with the Linaria 

 vulgaris x repens. The advent of the alien repens to the 

 native vulgaris led to the production of hybrids, the first year 

 about intermediate, the second in almost all stages between, 

 and in numbers much exceeding either of, the parents ; 

 then the gradual assertion of the native species, aided, per- 

 haps, by the chalk-rubble being gradually covered over with 

 other soil, till now only here and there a lingering hybrid 

 can be found. But L. vulgaris does not remain quite as it 

 was, for although no trace of the striae, or colour of repens, 

 could be observed in it, yet the plant, instead of being fairly 

 constant, shows variations in quite unexpected ways in 

 the width of the leaves, in the shape and direction of the 

 spur, in the colouring of the flowers, etc. 



Of course we must have more definite evidence as to the 

 actual disappearance of C. helvola and C. tetrastachya (both 

 of which Kukenthal named) from the precise locality on 



