312 O. Feistmantel — Contributions towards the [No. 4, 



species, is not quite complete ; and hence it is that he speaks only of forms 

 with complete leaf-whorls in which all the leaflets are equal. 



But from my more complete diagnosis is seen that there can be 

 distinguished two groups as regards the arrangement of the leaves. 



1. With complete whorls. 



This group would include the palaeozoic forms. 



2. With incomplete whorls. 



In this I place the Triassic forms of our Damiidas. A case ana- 

 logous to this we will find in Neuropteris, Bgt., wherein the bi- and tri- 

 pinnate fronds belong -to the palaeozoic epoch, while the single-pinnate 

 forms occur in the Trias. 



Sphenophyllttm trizygia, Ung., PL XV, Figs. 1, 2, 2a. 



1839. Trizygia speeiosa, Eoyle, 1. c. p. XXIX. p. 431, PI. 2. f. 8. 



18-15. — , Unger Synopsis, plant, foss. p. 114. 



1850. Sphenoph. speciosum, McClell., Report, p. 54. PI. XIV. f. 5. 



1850. Sphenoph. trizygia, Ung., Gen. et. sp. pi. f. pag. 71. 



1860. Sphenopkyllum, T. Oldham, M. G. Surv. II. p. 316. 



1865. Trizygia, W. T. Blanford, Raniganj coal field M. G-. S. Ind. III. p. 31. 



1876. Sphenoph. Trizygia, Feistmantel, Notes etc., Rec. Gr. S. I. IX. 3. p. 70. 



Caule articulato, tenerrimo, jluctuante (?) ; foliis senis in articulis, 

 totum verticillum haud formantibus, sed unilateral iter in tria paria dis- 

 positis ; pare sum-mo longissimo, imo brevissimo minimoque, medio medio- 

 cri. Foliis obovato -oblong e cuneiformibus ; tstervo medio istullo, nervulis 

 crebris aequalibus ex duobtts primariis regulariter dichotomis. 



Stalk articulate, very slender, floating (?) ; the leaves by six in 

 each articulation, not forming a complete whorl, but disposed on one 

 side of the articulum in three pairs ; the uppermost pair the longest, 

 the lowermost the smallest ; the leaflets oblong- cuneiform, ; no midrib, 

 but the veins numerous, equal, regularly dichotomous out of two chief 

 veins. 



Of this interesting species Mr. Wood-Mason has brought several nice 

 specimens, of which I figure two, to show the different sizes, the lower 

 leaflets being much longer than the upper ones. 



The collections of the Geological Survey contain also a great many 

 specimens of this species ; and other figures will be given in the ' Palaeonto- 

 logia Indica'. 



This species was first discovered by Mr. Eoyle and figured and 

 mentioned as Trizygia speeiosa ; with this name we find it still in Unger's 

 Synopsis (1845) and in the Mem. G. S. India. But McClelland in 1850 

 and Unger also in 1850 placed it with Sphenophyllum, Bgt., the former 

 keeping the older specific name, speciosum ; the latter substituting trizygia 



