









SYSTEMATIC POSITION OF THE DICTYOTACE33. 



463 











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On the Systematic Position of the Dictyotacea), with special 

 reference^' the Genus Dictyopteris, Lamour. By Thomas 

 Johns<&; B.Sc. (Lond.), University Scholar in Botany, 

 Demonstrator of Botany in the .Normal School of Science. 

 (Communicated by D. H. Scott, M.A., Ph.D., F.L.S., Assis- 

 tant Professor of Botany in the Normal School of Science.) 



[Read 19th December, 1889.] 







































(Plate XIII.) 



The Dictyot aceee , of winch the genus Dictyopteris, Lamour. 

 {Salyseris, Ag.), is a member, occupy, at the present time, much 

 the same sort of position in the Phceophycece (Brown Seaweeds) 

 that the Characece do in the Green Algse. Thus Falkenberg, in 

 his important paper on Alga? in Schenk's « Handbuch ' (Bd. ii. 

 P* 169), divides the chlorophyll-containing Thallophytes as 

 follows 

























* 

















































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Class I. Ploridese. 



(? Dictyot acece.) Marine Thallophytes, with unknown process 

 of fertilization ; systematic position still quite unknown- 

 Agreeing with the Floridea* in the formation of motion- 

 less tetraspores and spermatia, joining on to the Mela- 

 nophycesD in their vegetative organs. 



Class II. Alga*. 



Melanoph 



oph 



Inc 



cacete, Cutleriacea, Pheeosporea, Tilopteridea. 



Subclass II. CHLOEOPHTCBJ5. 



Class III. Diatomace*. 

 Class IV. Schizophycea. 



Messrs. Bennett and Murray, in their ' Handbook of Crypto- 

 genic Botany' (p. 255) "■" — — ""* n 



the Dictyotacece, until 



a — .v ajutany ^p. 255 ), would retain too xw«j»w«««'i — •» 

 ^ore is known of the process of fertilization, as an aberrant 

 order of Pl^e^*.^ t>„~* v,-«o«, in hi* article " Vegetable 



Diet 



« 





of Phaosporece. Prof. Vines, in his article " Vegetable 

 *h*tom " in the « Encyclopaedia Britannica ' (p. 127), places the 

 . . tacecB between the Cutleriacea and the Fucacea, a position 

 tt which I was at first inclined to place them. My object in 

 ««■ paper is to remove the Dictyotacece* from their anomalous 

 Position, on the ground of my own observations, more espe- 



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Cohn (Schenk, 



233) regarded the Dictyotacea 



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