71. AMENTIFER^. 397 



S. caprea, which latter is stated to occur in Faroe, where 

 the former would seem to be unknown, equally as any 

 other sub-species referred to S. cinerea in this volume. 



<4s^/^-/^^^ 1013. SaLIX NIGRICANS, i^We.s. 



Area * * 3 4 5 * * 8 * 10 11 12 13 14 15 16. 



South limit in Surrey ? Oxford ? Hereford ? 



North limit in Aberdeen, Perth, Argyle. 



Estimate of provinces 10. Estimate of counties 20. 



Latitude 51 — 58. Boreal type of distribution. 



A, A. regions. Inferagrarian — Midarctic zones. 



Descends to 100 yards, or lower, in Thames province ? 



Ascends to 800 yards, more or less, in East Highlands. 



Range of mean annual temperature 48 — 39. 



Native. Rupestral, &c. In drawing up the formula 

 for the distribution of this species, or group of species, I 

 cannot feel myself warranted in wholly rejecting the pro- 

 vinces of Thames, Ouse, and Severn; although not without 

 suspicion that the willows of these three provinces should 

 not be mingled with the really Highland or boreal willows 

 which are collected together under the common designa- 

 tion of " nigricans " or " nigricantes." 



/4c /!2//- ^^^ / C'^ 1014. Salix hastata, Linn. 



Area ^*84j)f******i(f** 15. 



South limit in Middlesex ? Norfolk ? 



North limit in Forfar. 



Estimate of provinces 3. Estimate of counties 3. 



Latitude 51—57. Local type of distribution. 



Agrarian region. Inferagrarian — Midagrarian zones. 



