STATISTICS OF THE ORDER CRUCIFER. 473 
the northern or central parts of the island. Elevation appears to 
be a bar to their general distribution in England. In the south 
of England we have no mountains; and lofty mountains or a 
higher latitude seem necessary for the existence of these species. 
The altitudinal range of some species of this Order has already 
been noticed, viz. that of the Cochlearias, which extend from the 
coast-line upwards to the summits of elevated mountains. These 
are both maritime and alpine plants, but their vertical range is 
not general: they fail in the intermediate spaces. Draba incana 
is found from the coast-level up to nearly 3500 feet above the 
sea, only in Scotland; but we have seen it in Wales (Merioneth- | 
shire) not more than 200 yards or so above the coast-lme. Car- 
damine pratensis and C. hirsuta have probably larger vertical and 
horizontal areas than any of our British plants. They ascend to 
upwards of 3000 feet in Scotland, and probably would attain as 
ereat an altitude here if there were any mountains of sufficient 
elevation, provided with a meadowy or boggy soil, in which they 
might grow. Arabis petrea descends to the altitude of 300 | 
yards (see ‘Cybele,’ vol. i. p. 140), and in its vertical range is pro- 
bably one of our most restricted plants; but it has a very consi- 
derable horizontal area. It might be expected a priori that the 
common Water-cress might have a larger vertical range than 
200 yards even in England. We judge merely from its wide 
horizontal area, and its plentiful distribution where there is water. 
Will any of our Yorkshire correspondents enlighten us on this 
point? We should be inclined, from the same assumption, to 
assien a greater altitude to Sisymbrium officinale than is given by 
the learned author of the ‘Cybele.’ But we leave this to those 
who have the means of deciding the point. We have seen the 
plant in Aberdeenshire on as high ground as 200 yards above the 
coast-line. We believe the Brassicas generally, without identi- 
fying species or varieties, grow at an elevation nearly as high as 
that which the Wild Mustard (Sinapis arvensis) reaches, 300 
yards at least. Both grow in cultivated places; and it may be, 
assumed as a position not to be disputed, that wherever the Turnip | 
or Rape is found in fields with other crops, it is only the re- 
mainder of the cultivated crop of the former year. Since the 
introduction of bone-dust and other artificial manures of no very 
great bulk nor weight, the cultivation of Turnip has been carried 
to a considerably greater elevation than formerly ; and the growth 
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