500 ISOCHIMENAL TEMPERATURES. 
based involucres, usually somewhat stellately downy. Heads of 
flowers more or less numerous, moderate in size. Phyllaries 
usually uniformly dark green, black when dried, nearly glabrous, 
occasionally paler at the edges, adpressed; outer lax, subsquar- 
rose, inner narrowest. Ligules glabrous. Styles livid. 
Woods, thickets, and heathery places in the valleys and dales, 
everywhere plentiful. Range of elevation, from the coast-level to 
400 yards. With reference to the anticipated objection to the 
name, to which allusion is made in the ‘Cybele Britannica,’ 
Fries writes, ‘‘ Nomen dorealis respicit reliquas species (lucidum, 
sabaudum, virosum, etc.) hujus stirpis, ultra quarum limites bo- 
reales longe progreditur: plantas boreales non indenticas fingas 
cum arcticis. Occurrit quidem in Europa australiori, sed in 
alpibus et montibus tantum, ut plurime plante planitierum 
borealium.” | 
In conclusion, we may sum up the geography of the Hieracia 
of North Yorkshire and Teesdale as follows :— 
Four species (three of which are confined to Teesdale) occur 
only amongst the dales of our western moorlands, viz. aicwm, 
cerinthoides, pallidum, corymbosum. Four species are common 
to the moorlands on both the eastern and western sides of the 
Vale of York, viz. murorum, cesium, gothicum, crocatum; and 
the remaining five occur amongst both ranges of hills, and also 
in the midst of the central valley, viz. Pilosella, vulgatum, tri- 
dendatum, umbellatum, boreale. 
Thirsk, 1, 10, 1856. 

Report of Observations on the Deterioration of Isochimenal Tem- 
peratures in proportion to Altitude in the North of England. 
The lines of winter temperature exercise such a predominant 
influence on the determination of the boreal limits of arborescent 
species and perennial herbaceous plants, that they claim the deep 
attention of botanical geographers. In the winter of 1854-5, with 
a view to collect data relative to this question, a series of obser- 
vations were instituted under the auspices of my valued friend, 
T. Sopwith, Esq., of Allenheads and Newcastle, a gentleman 
well known as a practical and theoretical geologist, and at that 
time President of the Tyneside Naturalists’ Club. Compared 
thermometers were stationed, one of them at the head of the 
