Ser. Mela^ospermejE. Fam. Bictyoiea. 



Plate CCXLVIII. 



PUNCTARIA TENUIS SIM A, Grev. 



Gen. Char. Frond undivided, membranaceous, flat, ribless, with a naked, 

 scutate root. Fructification scattered over the whole frond, in minute, 

 distinct dots, composed of roundish, prominent spores, intermixed 

 with club-shaped filaments. Punctaria (Grev.), — from punctum, a 

 dot ; the fruit being in dots, scattered over the surface. 



Punctaria tenuissima; frond sublinear, very thin, transparent. Grev. 



Punctaria tenuissima, Grev. Alg. Brit. p. 54. Hook. Fl. vol. ii. p. 279. 

 Earv. Man. p. 34. 



Punctaria undulata, /. Ag. Spec. vol. i. p. 72. 

 Ulva plantaginifolia, Lyngh. p. 31. t. 6. (fide J.Ag.) 

 Diplostromium plantagineum, Kg. Phyc. Gen.y. 298. 

 Hab. Parasitical on Zostera marina, Chorda filum, &c. near low -water 

 mark. Annual. Summer. Bute, Br. Greville. Appin, Captain 

 Carmichael. IS; ear Dublin, W.H.H. ; probably common. 



Geogr. Distr. Atlantic Shores of Northern Europe, Baltic Sea. North "West 

 Coast of France. North America. 



Descr. Fronds, 2-8 inches long, 1-3 lines wide, very densely tufted, covering 

 the plant on which they grow with innumerable slender wavy ribbons, 

 tapering to the base and apex, but linear for the greater part of their length, 

 sometimes ending bluntly ; the margin waved or curled, and either entire, 

 or remotely and irregularly toothed. Colour, a very pale shade of brou nish 

 olive, or horn -colour, sometimes hyaline. Substance exceedingly thin and 

 delicate, adhering to paper. Structure beautifully areolated. Fruit unknown. 



Two species of Punctaria have already appeared in this work, 

 and the one now figured completes the representation of the 

 British kinds. The present species has never been found in a 

 state of fruit, and hence some botanists (among others my valued 

 friend Mrs. Griffiths) regard it as the young of some other species; 

 perhaps of F. latifolia, with which its substance more nearly 

 agrees, than with that of P.plantaginca. But its great difference 

 in form seems to forbid such an opinion being hastily adopted. 

 particularly as young P. latifolia may be found of much smaller 



