88. PTKRIDIOIDES. 299 



not pi'epared to say with certainty. There is a vague in- 

 timation of its occuiTence much higher than I have indi- 

 cated above ; namely, " in Ffynnon frech, a small lake 

 near the top of Snowdon". The counties of Salop (Mr. 

 Griffith, in With. Arr.) and Glamorgan CMr. Moggridge, in 

 Dilln'. Mat.) have been reported for the Isoetes ; but -pos- 

 siblj^ the Littorella may have been mistaken for it, as in 

 some other instances within my knowledge. Mr. Sjme 

 has shown me specimens of Littorella, labelled as Isoetes, 

 which were sent to the Botanical Society of London so 

 lately as December, 1851. The counties above mentioned 

 for the south and north Kmits, together with Merioneth, 

 Caernarvon, Denbigh, Northumberland, Westmoreland, 

 Cumberland, (Fife ?), Stirling, Perth, Forfar, Dumbarton, 

 and Argjde (Bute), rest on good authority. 



1419. PiLULARIA GLOBULIFERA, Linn. 



Area 1 2 3 4 5 6 7 8 9 10 11 * 13 14 15 16 17. 



South limit in Cornwall, Dorset, Hants, Sussex. 



North limit in Sutherland. 



Estimate of provinces 17. Estimate of counties 50. 



Latitude 50 — 59. British type of distribution. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends to the coast level, m the Peninsula. 



Ascends to 300 yards, in North Wales. 



Range of mean annual temperature 52 — 45. 



Native. Lacustral, Uliginal. Though widely spread, 

 this is somewhat thinly scattered in Britain, if we trust 

 entii-ely to the published records. But a plant so incon- 

 spicuous in itself, and so frequently submersed, is doubt- 

 less often overlooked ; and hence I assume that the actual 

 records of its occurrence in scarcely 40 counties will be 



