1160 



rather wide cellular space, forming the so-called central nerve. The 

 supposed lateral nerves, also, are only apparent in that plant, being 

 visible solely after the leaves have been subjected to pressure, and are 

 merely the result of it. The lower leaves of P. flabellatus are of equal 

 thickness throughout, and have their sides uniformly curved inwards 

 so as to form a segment of a cylindrical tube ; when dry, 3 or 5 rather 

 prominent ribs are formed on the back, by the shrinking of the inter- 

 mediate cellular spaces : their end is abruptly but shortly cuspidate. 

 The upper leaves, including probably all those that float at or near to 

 the surface of the water, are much narrower, and very gradually acute ; 

 3-nerved, but the lateral nerves often so close to the margin as to be 

 nearly uudistinguishable from it. 



It is probable that P. flabellatus was known to Hudson ; for he has 

 a plant named P. marinus, " Habitat in fossis maritimis .... prope 

 Sheemess abunde" (ed. 1, p. 63),." In insula Shepey abunde" (ed. 2, 

 p. 77), which he supposed to be the P. marinus, Linn. : also that the 

 plant found at Yarmouth, as noted below, is the P. marinus, Hurts. ; 

 for Mr. Woodward is recorded (Wither. Bot. An*, ed. 3, ii. 214) to 

 have gathered what is so called by Withering at that place. Fries 

 has shown (Novit. Fl. Suec. ed. 2, p. 52 and 55) that the name P. 

 marinus, Linn., refers rather to the P. filiformis, Nolle, than to either 

 P. pectinatus, P. flabellatus, or P. zosteraceus. As the name has been 

 employed to designate each of them, by one or more authors, it seems 

 desirable to allow it to fall out of use, for its retention only tends to 

 cause confusion. At all events, the P. flabellatus has no claim to be 

 considered as the P. marinus of Linnaeus, although it probably is that 

 of Hudson and Withering. 



P. flabellatus is found at Denver, Norfolk ; in the canal near Bath, 



Somerset ; Mr. Kirk meets with it near Coventry, Warwickshire ; 



Mr. Syrae, at Gravesend, Kent ; the Rev. W. W. Newbould has 



brought it to me from the fen-ditches between Hull and Hedon, 



Yorkshire, and from near Burnham, Norfolk ; it has been gathered by 



the Rev. Kirby Trimmer in salt-water ditches near Great Yarmouth ; 



and it is recorded in the ' Flora of Hertfordshire ' as growing in the 



river Lea at Hertford and Ware (p. 276), and in the canal near Tring 



(App. p. 17). 



Charles C. Babington. 



November, 1853. 



EDWARD NEWMAN, PRINTER, nEVONSHIRE STREET, RISHOPSGaTE. 



