10 THE JOUEXAL OF BOTA?«"Y 



Silverwell Moor (1) : a dark green robust plant growing in dense 

 cushions in the bed of the stream. — aS'. undulata (L.) Dum. Goon- 

 havern Moor (1) and Penhallow Moor near Newlyn East (1) ; Upper 

 Fowey Eiver ; stream at Bolventor (2). Perianths occur on the 

 Goonhavern plants. — B. irrigua (Nees) Dum. Damp sides o£ 

 paths, Yentongimps and Silverwell Moors (1). 



Radula complanata (L.) Dum. Frequent near Polperro and 

 Looe (1), but oftener on rocks than on trees. Capsules are freely 

 produced. On a rock-face at Trenevvan (2) occurs a darker plant 

 with abundant gemmre which may be B. Lindhergii Gottscbe, but 

 I have not been able to find the inflorescence. 



Madotlieca Thuja (Dicks.) Dum. On "stone hedges," i.e. 

 boundary walls of loose stones and earth, at Polperro. — M. platy- 

 pliyUa (L.) Dum. On rocks at Polperro and Muchlarnick (2). 



Lejeiinea cavifolia (Ehrh.) Lindb. var. heterophylla Carr. 

 Polperro (2). 



Frullania tamarisci (L.) Dum. Frequent on rocks and some- 

 times on trees ; perhaps most plentiful on rocky slopes b}" the sea. — 

 F. d Hat at a (L.) Dum. Common. 



Anthoceros piinctatus L. Silverwell and Wheal Butson Moors 

 (1) ; damp lane near Lansallos Church (2). The West Cornwall 

 plant is as large as A. Musnotl, but the section is that of A. pimc- 

 tatus. — A. IcBvis L. Damp meadow at Ventongimps (1). A rather 

 common plant on damp soil and moist banks in the area between the 

 Fowej' and Looe Kivers (2). 



NOTES ON BRITISH POTAMOGETONS. 

 Bx Arthue Bex:nett, A.L.S. 



The following notes are suggested by a peiTisual of Herr 

 Hagstrom's Critical Hesearclies on the genus, noticed in this Journal 

 for 1917, pp. 115-117. The species follow the order of Lond. Cat. 

 ed. 10. The northern range of each species is shown because the author 

 makes a prominent feature of this, sometimes b}'' latitude, some- 

 times by the year-isotherms. It seems to me that latitude is preferable, 

 as this can be seen on any map, whereas physical maps do not always 

 agree as to the isothermal lines, and there is the trouble of reducing 

 the Centrigrade (employed by the author) to the Fahrenheit scale. 

 The southern range cannot be so well shown, as authors differ as to 

 the identity of southern with northern species. I have added after 

 each name a reference to the page in which the species is dealt with : 

 this is the more necessary in that the author in his otherwise excellent 

 index has cited all his references to each plant without indicating the 

 principal one in thicker type, as is now customary : — 



P. NATA^'S L. (p. 191). Sweden north to Swedish Lapland; 

 Norway to 70° 3' n. lat. ; Finland to 69^^ n. lat. ; Scotland to the 

 Shetlands. 



Sub- var. maximus Baagoe. Leaves 110 X 70 mm. ; stipules 110 

 mm. long. Barningham, E. Suffolk, E. F. Linton. Pembroke (1883), 

 Ridley, 



