TETRAND. TETRAG. 59 



Hab. Ditches and ponds, not very common. Light/. In the Clyde, 



Ure. Ft. Aug. % . 

 Not being acquainted with this, as really distinct from the preceding, 



I quote Smith's description. 1 should doubt its being a good 



species. 



1 1. P. pusillum {small Povd-tveed), " leaves linear opposite and 

 alternate distinct spreading from the base, stem cvlindrical" 

 (Sm.). nglitf. p. 124. E. B. t. 215. 



Hab. Ditches and stagnant waters, Light/. Common, Ilopk. Ft. 

 July. 2/. 



Having no authentic specimens of this species in my possession, 

 I can add nothing from my own observation to the above charac- 

 ter from Smith. 



12. P. pectinutum {femitl-leaved Pond-tveed), haves distichous 

 setaceous alternate sheathing, stipules scarcely any, spike of 

 flowers interrupted. Light/. p. 123; andp. \ 24 { P. ma) hium). 

 E. B. t. 323. 



Hab. Rivers, lakes and salt-water ditches. Lake of Rescalin, near 

 Forfar, D. Don. River Tweed, near Kelso, Maugh. 



'ITiis species, from the leaves being rather closely set and regularly 

 distichous, has, when growing, a remarkably pectinated appear- 

 ance. Sheaths of the leaves long. The spike is interrupted, and 

 as well as the general habit not unlike Riippia maritima. 



15. RUPPIA. 



1. R. marilima {Sea Ri/ppia). Light/, p. 124. E. B. t. 136. 



Hab. Stagnant waters by the sea-side, not uncommon, as at Glen- 

 Elg, Inverness-shire, Light/. Salt-water pools at Guillon Links, 

 Edinb., Ma«o^/t. Aberlady Bay, Mr.Arnutt. F/. July, Aug. If.. 



Stems slender, filiform, flexuose, branched, leafy. Leaves linear- 

 setaceous, sheaths an inch long, membranaceous, inflated. Spadix 

 at first very short, included in the sheaths, with 2 naked green^oit;- 

 ers one above the other, on opposite sides. Anthers large, sessile, 

 subquadrate, bursting horizontally. Germens resembling 4 minute 

 tubercles in the centre between the anthers. After flowering, the 

 spadix lengthens remarkably, five or six inches or more, and be- 

 comes spirally twisted, so that it may extend or contract itself with 

 the rising or falling of the waters ; at the same time the germens 

 swell, and rise upon footstalks (as the fruit ripens) of an inch in 

 length. Drupes 4, ovate, acuminate. — For a more full account than 

 I am able to insert here of this highly curious plant, and a full ana- 

 lysis of the parts of fructification, I must refer to the New Series 

 of the Flora Londinensis. 



16. SAGINA. 



I. S. procumlens {procumbent PeorZ-t^or/), perennial glabrous, 

 stems procumbent, leaves shortly mucronate, petals much 

 shorter than the cal., caps, longer than the cal. Light/, p. 

 125. E.B.t.nm. 



Hab. Sandy and gravelly soils, frequent. Fl. June, July. 11 . 



