81. FLmiALES. 11 



P. pectinatus grows in Orlaiey and Shetland ; but whether 

 these northern habitats belong to P. pectinatus, or to P. 

 filiformis solely, must now be held doubtful. 



1120. PoTAMOGETON PUSiLLUS, Linn. 



1120*. " PoTAMOGETON TRICHOIDES, Cham." 



Ai-ea 1 2 3 4 5 6 7 8 9 10 11 * 13 14 15 16 * 18. 



South limit in Cornwall, Isle of Wight, Kent. 



North limit in Orkney ; — Moray, Argyle. 



Estimate of provinces 17. Estimate of counties 70. 



Latitude 50 — 60. British tjqpe of distribution. 



Agi'arian region. Inferagrarian — Superagi'arian zones. 



Descends to the coast level, in the Peninsula. 



Ascends to 100 or 200 yards, in England. 



Kange of mean annual temperature 52 — 46. 



Native. Lacustral. Southward from Orkney (whence 

 I possess a specimen, labelled " P. gramineus ?" by Dr. 

 Gillies) there appears no locality known for the present 

 species until we reach Moray and Banff, on the east side 

 of Scotland, and Islay and Cantire, on the west. The 

 total number of counties recorded for it scarcely amoimts 

 to 50 ; but those from wliich it thus appears to be absent, 

 are scattered among the rest ; and are those, with very few 

 exceptions, for which our lists of the commoner species 

 are the least complete. 



Under name of P. trichoides, another alleged species is 

 described in Babington's Manual, and stated to have been 

 found in Norfolk, by the Eev. I^'by Trimmer; more 

 doubtfully also reported from Glamorgan, as found by 

 Mr. Moggi-idge (Phytol. iii. 1059). Having seen no speci- 

 men, I am unprepared to say whether it is a real species, 

 or merely a book- species; but it stands for a true species 



