82. LEMNACE^. 29 



localities between York and Edinburgh, and also north- 

 ward of Liverpool and Manchester, on the westward side 

 of the island. There can be little doubt that the south- 

 ern line will be carried into Cornwall, when the plants of 

 that covinty are more completely ascertained. 



1141. Lemna trisulca, Linn. 



Area 1 2 3 4 5 6 7 8 9 10 11 * * 14 15. 



South limit in Devon, Isle of Wight, Kent. 



Nortli limit in Forfar. 



Estimate of provinces 15. Estimate of counties 60. 



Latitude 50 — 57. English type of distribution. 



Agrarian region. Inferagrarian — Midagrarian zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 100 or 200 yards, in England. 



Range of mean annual temperature 51 — 47. 



Native. Lacustral. Ascends to the confines of the 

 superagi-arian zone by its localities in Forfarsliire, and 

 V1&.J perhaps eventually be found to belong to the British, 

 rather than to the English, type of distribution ; although, 

 while the name appears in only four Scottish lists (Ber- 

 wick, Roxburgh, Edinburgh, Forfar), and for counties all 

 in the southern half of Scotland, the species will of course 

 be assigned to the English type. On the western side of 

 the island, I find no locality reported farther northward 

 than South Lancashire ; but have ventured to include the 

 two next provinces, Lakes and West Lowlands, in the pro- 

 vincial estimate. 



