10 81. FLUVIALES. 



1119. POTAMOGETON PECTINATUS, Linil. 



1119, b. PoTAMOGETON MARiNus, Linn. 



1119, C. PoTAMOGETON FLABELLATUS, Bab. Mail. 3. 

 1119, d. PoTAMOGETON FILIFORMIS, " Nolte." 



Ai-ea 1 2 3 4 5 * 7 8 9 10 11 * 13 14 15 * 17 18. 



South limit in Cornwall, Isle of Wight, Kent. 



North limit in Shetland, Orkney. 



Estimate of provinces 17. Estimate of counties 70. 



Latitude 50 — 61. British type of distribution. 



Agrarian region. Inferagi-arian — Sui^eragrarian zones. 



Descends to the sea level, in the Peninsula. 



Ascends to 100 or 200 yards, in England. 



Range of mean annual temperature 52 — 45. 



Native. Lacustral. Whatever decision may be given 

 eventually, on the distinctness of the plants mcluded 

 under the four names above quoted, it is impossible at 

 present to describe their distribution separately ; the 

 name " pectinatus," under which most of the localities 

 are recorded, having been usually employed indetermi- 

 nately for anj, or comprehensively for all, of the alleged 

 species. If P. marinus and P. filiformis are synonymous 

 names for the same plant, the group becomes divisible 

 into thi'ee, which may be distinct si)ecies. P. flabellatus 

 (P. zosteraceus, Bab. Man. edition 2) is said to occur in 

 Hants (Mr. Borrer), Middlesex (Dr. J. A. Power), Herts 

 (Flo. Hertf.), Gloucester (]\Ir. Thwaites), Leicester (Miss 

 Kirby, — but doubtful), and likely enough may be ah-eady 

 known, if not recorded, in other counties. P. filiformis is 

 stated to occiu* in the counties of Leicester (Rev. A. Blox- 

 am), Berwick and Forfar (Bab. Man.), in Ross and Orkney 

 /"A/iSi-w/ ^, (Ml'- J. T. Sj-me). According to Neill and Edmondston, 



