104 M. Brongniart on the Relations of the 



over, they are dichotomous with a bifurcation which is distinct, 

 and forms a very obtuse angle. A few ferns only having a sim- 

 ple flabelliform frond, present a structure tolerably analogous to 

 that of the leaflets of Noggerathia : such are Schizea latifolia and 

 elegans, but the general form of the leaf is very different. 



These structural characters of the leaves appear to exclude all 

 real analogy of the fossil plants which we are considering with 

 the two families, the Palms and Ferns. 



But there is another family very widely diffused among the 

 primary creations of the vegetable kingdom, which presents a 

 much more marked analogy with Noggerathia in the structure of 

 its leaves ; it is that of the Cycadece. We know that the Cy- 

 cadecB, long since placed by botanists sometimes near the Ferns, 

 sometimes the Palms, have been considered by all recent authors, 

 especially since the beautiful publications of L. C. Bichard and 

 Du Petit Thouars, as intimately allied to the Conifer (2, and form- 

 ing with them the remarkable group of gymnospermous dicoty- 

 ledons. But if the CycadecB and Conifer ce are united by the 

 most important points in their organization, they differ extremely 

 in their general aspect, in which the Cycadece resemble the Palms. 

 Like them, the Cycadem have pinnate leaves with linear lanceo- 

 late or oblong and almost spatulate leaflets. However, the struc- 

 ture of these leaflets is very different in these two families. In 

 Cycas they are traversed by a single median nerve ; on the con- 

 trary, in Zamia, and especially in the American Zamice, each leaflet 

 is traversed by slender and numerous nerves, which are of perfectly 

 equal size, arise directly from the base of the leaflet, simple and 

 parallel when the leaflet is linear or oblong, slightly divergent 

 and bifurcate at a very acute angle when the leaflets are obovate 

 or spatulate. In short, the neuration is exactly the same as that 

 of Noggerathia, The general form of these leaflets is also very 

 analogous when we compare certain species of Noggerathia, such 

 as N. foliosa and 5p«^M/«, with some species of American Zami(e, 

 as Zamia furfuracea, integrifolia and pygmcea. Other species 

 are further removed from the existing CycadecB by the form of 

 their leaflets; but the characters of the nervation remain the 

 same, and their importance is evidently much greater than that 

 of the form of the leaves. Thus the Noggerathice appear to me 

 clearly to approach the Cycadece. in the structure of their leaves, 

 and to belong to the division of the gymnospermous dicotyledons. 

 But the Cycadece and the allied famihes are frequently arbo- 

 rescent plants, furnished with both male and female flowers, and 

 with seed of a considerable size. May we not find portions of 

 these organs in the strata in which Noggerathice occur, which 

 would confirm and more accurately determine the affinities of 

 these plants ? 



