81. FLUVIALES. 19 



1130. POTAMOGETON LANCEOLATUS, Sm. 



Area 1 * * * 5 * 7 * * 10 * 12 13 * 15 * * 18. 



South limit in Somerset ? 



North limit in Shetland ? 



Estimate of provinces 8. Estimate of counties 13. 



Latitude 51 — 61. British (?) tj^oe of distribution. 



Agi-arian region. Inferagrarian — Superagrarian zones. 



Descends to the coast level, in England. 



Ascends to 100 yards, more or less, in England. 



Range of mean annual temperature 49 — 45. 



Native. Lacustral. A doubtful species, the localities 

 of which are too much confused with those of P. hetero- 

 phyllus, to allow of its distribution being correctly shown 

 by the formula. Has been stated to occur in Somerset 

 (Dr. Southby), Gloucester [(Mr. Buckman), Anglesea (Mr. 

 J. E. Bowman!), York (Mr. James Ward; Mr. Joseph 

 Woods ?), Lake-Lancaster (Mr. F. J. Hort ?), Cumberland 

 (Mr. C. C. Babington), Dumfries (Mr. William Stevens), 

 Kirkcudbright (Mr. Peter Gray), Forfar (Don Ace; Flo. 

 Forf.). Kincardine (Hook. Scot. ; Bab. Man.), Aberdeen 

 (Northern Flora ; Flo. Abred.), Moray (Rev. G. Gordon ; 

 Br. Flo. ; &c.), Shetland (Flo. Shetl.). The formula is 

 filled up above in accordance with these alleged localities ; 

 but in the after portions of this work, where the details 

 will requii'e to be connected and generalised, it may 

 probably be found expedient to sink P. lanceolatus under 

 the more comprehensive P. heterophyllus. 



