288 M. Brongniart on some Fossil Vegetables. 



that, among the pahus, the doum, a palm with dichotomous 

 stem, so common in Egypt, had been destroyed by some revo- 

 lution of the globe, all the botanists would consider a simple 

 stem as a general character of the plants of this family, and 

 perhaps would hesitate to assign a place in this group to a 

 plant, the organization of which would appear to separate it 

 from all the other species known. We are not acquainted with 

 any circumstance that would induce us to believe that the 

 family of ferns, the arborescent species of which are still so im- 

 perfectly known, does not contain plants with stems thus divid- 

 ed. The characters deduced from the form and disposition of 

 the bases of the petioles, and from the disposition of the 

 vessels in these petioles, characters which are only observed 

 among the ferns, appear to us of much greater importance, and 

 decide in our opinion the place which these vegetables ought to 

 occupy. 



All the families of phanerogamous monocotyledonous plants 

 which contain arborescent species, present these two forms of 

 stem. It is therefore probable, that when the equinoctial zone 

 shall be better known to us, cycases, zamise and ferns with 

 dichotomous stems, will be discovered, as we already know dra- 

 conae, yuccse, and palms, which present this organization. Per- 

 haps, also, these vegetables, so remarkable for their form, their 

 magnitude, and we may even say their elegance, have ceased to 

 exist at the surface of the earth, and their remains will serve to 

 perfect our ideas regarding several families of plants, of which 

 the present vegetation of our globe no longer presents but im- 

 perfect fragments, in the same manner as the ancient world 

 has already served to fill up several voids of the animal king- 

 dom. 



Eocptanaticm of Plate VI. 



Fig/1. Sigillaria Hippocrepis. Ad. B. 



Sigillaria with flattened ribs, eight lines broad ; bark smooth ex- 

 ternally, striated internally ; cicatrices semi-elliptical, truncated 

 beneath, or in the form of a horse's shoe, marked with three vas- 

 cular fasciculi above ; internal cicatrices simple, ovaL 

 Found in the coal mine of Mons. 



3 



