See. MELANOSPERME^. ( 81 ) Fam. DICTYOTEii;, 



Plate CLVIII. 

 DICTYOTA BICB.OTOMA.—LamoKr. 



Gen. Char. — Frond membranaceous, flat, witliout midrib, irregularly dichotomous, 

 cellular ; cells large, quadrate ; root, a mass of woolly fibres. Fructification : 

 scattered clusters of spores (tetraspores), beneath the surface of the frond, through 

 which they finally burst, or on distinct plants; single spores (?) similarly scattered 

 under the sui-face. Name from SUtvov, "a net," referring to the reticulated 

 structure. 



DiCTYOTA dichotoma. — Frond scarcely stalked, regularly dichotomous ; 

 segments linear, snberect ; axils and apices rounded ; spores mostly 

 collected in roundish oval sori. 



DiCTYOTA dichotoma. — Lamour. Ess. p. 58; Grev. Alg, Brit. p. 57, t. 10; HooTc. 

 Br. Fl. vol. ii. p. 280 ; Wyatt, Alg. Damn. No. 10 ; Duhy, Bot. Gall. 

 p. 954; Menegh. Alg. Ital. et Balm. p. 224; Endl. 3rd Suppl. p. 24 ; 

 Mont. Fl. Alg. p. 30 ; Harv. P. B. plate 103 ; ffarv. Man. p. 39; 

 ffarv. Syn. p. 33 ; Atlas, plate 10, fig. 37 ; Harv. N. B. A. part 1, 

 p. 109 ; /. G. Agardh, Sp. Gen,. Alg. vol. i. p. 92. 



ZoNAKiA dichotoma. — Ag. Sp. Alg. vol. i. p. 133 ; Ag. Syst. p, 266 ; Hook. 

 Fl. Scot. vol. ii. p. 90 ; Grev. Fl. Edin. p. 297. 



DiCHOPHYLLiuM vulgarc. — Kiltz, Phyc. Gen. p. 337, t. 22 ; vol. ii. f. 1-4. 



DiCHOPHYLLiUM dichotomum. — Kiltz. 1. c. p. 338. 



Haliseris dichotoma. — Spreng. Syst. Veg. vol iv, p. 328. 



Ulva dichotoma.— Huds. Fl. Angl. 2nd edit. p. 568, 1st edit. p. 476 ; Lightf. 

 Fl. Scot. p. 975, t. 34 ; With. Br. PI. vol. iv. p, 124 ; Engl. Bot. 

 t. 774 ; Lyngl. Hyd. Dan. p. 31, t. 6c. 



Var. /3, intricata. — Frond very narrow, irregularly branched and twisted. 



DiCTYOTA dichotoma, /3 intricata.— Grev. Alg. Brit. p. 58; Menegh. Alg. Ital. 

 et Dalm. p. 227 ; Harv. P. B. plate 103 ; Harv. Man. p. 39. 



DiCTYOTA dichotoma, j8 implexa. — /. G. Agardh, Sp. Gen. Alg. vol i. p. 92. 

 DiCTYOTA implexa. — Lamour. 1. c. ; /, Ag. Alg. Medit. p. 37; Mont. Fl. Alg. 

 p. 30. 



DiCHOPHYLLiiTM implcxum. — Kiitz. Phyc. Gen. p. 338. 



Hab.— Parasitical on various Alg«, also growing on stones, old shells, and rocks in 

 tide-pools, as well as in deep water. Annual, Summer. Both varieties common. 



Geogr. Dist. — Atlantic Ocean from the Norwegian shores to the tropic ; Southern 

 Ocean ; Western shores of South Afnerica ; Cape of Good Hope ; New Zealand. 



Description, — Root minute, covered with matted fibres. Stem, scarcely 



VOL. III. ^ 



