Maskell. — On a neiv Variety of Desmid. 



S25 



Art. LIV. — On a neiv Variety of Desmid. 



By W. M. Maskell, F.E.M.S. 

 [Read before the Wellington Philosophical Society, 2ith February, 1886.] 



Genus Triploceras, Bailey. 

 Triploceras tridentatum, Maskell ; var. superbum, var. nov. 



Frond slender, elongated, cylindrical, very slightly depressed 

 at the middle. 



Denticulate lateral projections of the segments large, some- 

 what prominent, tri-dentate, the 

 middle tooth the largest. Edges 

 of frond between the projections 

 slightly curved inwards, so that 

 the segments appear as if with 

 several toothed transverse rings. 

 Denticulations pointing at right 

 angles to segment near the con- 

 striction, and slightly forward near 

 the extremities. The small pro- 

 cesses at the base of the terminal 

 tridentate prolongations sharply 

 pointed forwards, not tri-apiculate. 

 Terminal processes, 2, sub-rectan- 

 gular, tri-dentate. 



Endochrome, not very dark- 

 green. 



Length of frond, about 625 /u ; 

 breadth near constriction, about 

 50 ,x. 



From Wainui-o-mata, near Wel- 

 lington. 



This is a more ornate and 

 elegant plant than T. tridentatum, 

 or its other variety, cylindricum, 

 on account of the more complex 

 lateral denticulations. In the 

 locality mentioned it seems to be 

 somewhat abundant : it is quite 

 constant in its characters. 



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