25 



pith. My Dadoxylon annulatum shows structures approach- 

 ing to this last. 



Eenault has constituted a new genus (May, 1889) under 

 the name Ptychoxylon, in which the wedges of the woody 

 cylinder extended inwards, and are then bent so as to simu- 

 late internal woody layers. 



All these stems are regarded as probably gymnospermous, 

 and with the different types of Dadoxylon, the Cordaites and 

 Tylodendron, serve to give some account of the trees from 

 which the multiform nutlets and seeds of the Carboniferous 

 and Erian were derived. 



The genus Nosggerathia, like that of Flabellaria (Cor- 

 daites), dates from the time of Sternberg, and his N.foliosa 

 is the original type, to which, however, a somewhat miscel- 

 laneous group of species has been added by subsequent 

 authors. Some of these, instead of the pinnate leaves of 

 the original species, have simple leaves spirally arranged 

 and decurrent on the stem. This is the case, for example, 

 with N.flabellata of Lindley and Hutton, which, on this 

 and other grounds, has been placed with some other 

 species by Schimper ] in a new genus Psygmophyllum, while 

 Saporta 2 places them in his genus Ginkgophyllum, suppos- 

 ing them to be akin to the modern Ginkgo or Salisburia. 



These two types of Noeggerathse agree with one another, 

 and differ from Cordaites in the flabellate form and forking 

 venation of the leaves. The nearest approach to the Cor- 

 daites is that of the leaf of JV. flabellata to that of C. patulus 

 Grand Eury. 3 Saporta states that the ordinary Noeggera- 

 thiaB (N. foliosa) bear their fructification on the surface of 

 modified leaves, and he is inclined to place them near to the 

 Cycads. On the other hand, he regards the second typo 

 (N.flabellata, &c.~) as more nearly allied to the taxine Coni- 

 fers, though their fructification is not certainly known. 

 Lacoe's specimen, now under consideration, would, how- 



1 Palseontologie Vegetale. 



2 Evolution de Monde Vegetal 



3 Saporta I. c. 



