34U KENTISH BOTANY. [November, 



This is probably a very healthy situation ; for these houses on 

 the top of the cliff have the benefit of the fresh and cool morning 

 gale from the downs, and also of the sea-breeze which blows 

 steadily from some point of the south during the day. 



Thus at Folkestone ended one of the most agreeable and suc- 

 cessful botanical excursions either of us ever had, though we 

 were far from being novices in this way of holiday-spending and 

 plant-seeking. Before commending to our readers particular 

 parts of the country to their special notice, some observations 

 remain to be made on certain species, especially in reference to 

 their distribution. 



It is assumed by some botanical observers whose opinions on 

 the distribution of species are entitled to much deference, that 

 certain plants are native to the valley of the Thames, which 

 means that there is no suspicion of foreign origin or introduction 

 attaching to them ; and that others are only entitled to rank as 

 denizens, which means that their claims are doubtful, or that 

 they occupy a neutral position, or lie between the unsuspected 

 and the suspected natives, like Mahomet's coflBn suspended in 

 the air between earth and heaven. 



Me7'curialis annua is plentiful in the valley of the Thames, 

 both above and below London, and it was almost if not quite as 

 abundant at and below Canterbury. This species passes muster 

 as a native, though not frequent in England. In all these loca- 

 lities M. annua is associated with Diplotaxis muralis, and this 

 latter plant is called a " denizen.'' The late Dr. Bromfield, in 

 vol. iii. of the ' Phytologist,^ o. s., p. 823, produced many reasons 

 why M. annua should not be reckoned a true native. 



This plant, the annual or French Mercury (see ' Phytologist,' 

 O.S., vol. iii. p. 823), was profusely distributed by waysides, in 

 cultivated places, as well as on rubbish and in gardens, in villages 

 and towns in all parts of our route from Canterbury to Folkestone. 



Another plant of cultivation which we found, it may be said, 

 everywhere, is Diplotaxis muralis, probably long overlooked and 

 mistaken for a state of D. tenuifolia. This plant is extending in 

 all directions, and it appears, like several other species, to evince 

 a special predilection for railways. Only the other day, Septem- 

 ber 18th, it was observed plentifully on the gravel adjoining the 

 platform at Wraysbury station of the South-Western, London 

 and Windsor line. 



