AEEANGEMENT OF FOSSIL VEGETABLES. 179 



7. Clathraria. — Stem neither channelled, nor jointed ; impressions in the form of 



rounded disks, disposed in quincunx.' 



8. Sagbnaria. — Stem without joints, or furrows, covered with conical rhomboidal tubercles 



disposed in quincunx, having at their upper extremity an impression in the form of a 

 disk.^ 



9. SxiGMARtA. — Stem without joints, or furrows ; impressions rounded, distant, disposed in 



quincunx.^ 



FOLIAGE. 



10. Lycopodites. — Leaves linear, or setaceous, without ribs, or traversed by a single rib, 

 inserted all round the stem, or in a double row. 



This genus is subdivided into four sections, as follow : — 



a. Leaves narrow, lanceolate, inserted in a regular manner all round a stem having 



the characters of Sagenaria. 



b. Leaves setaceous, inserted in a double row only ; stem not reticulated. These he 



considers as the proper Lycopodites. 



c. Leaves broad, without any apparent ribs, inserted irregularly all round the stem. 



These differ much from the rest of the genus. 



d. Leaves blunt, short, closely applied to the stem. 



Class IIL — 11. FiLiciTES. — Frond disposed on a flat surface, symmetrical; secondary rib 

 simple, forked, or rarely anastomosing. 



These are divided Into five sub-genera : — 



a. Glossopteris. — Frond simple, not jagged, traversed by a single mid-rib, without 



distinct secondary ribs. 

 h. Sphenopteris.—Vm.a.xxles wedge-shaped, rounded or lobed at the extremity ; ribs 



palmate or radiating from the base of the pinnule. 



c. Neuropteris. — Pinnules rounded, not lobed, nor adhering to the rachis by their base ; 



ribs scarcely visible beyond the base, in general very distinct, and two-forked. 



d. Pecopteris. — Frond pinnatifid ; pinnules adherent by their base to the rachis, 



traversed by a mid-rib ; secondary ribs pinnate. 



e. Odontopteris. — Pinnules adhering to the rachis by the whole of their base ; mid-rib 



none ; secondary ribs running out perpendicularly from the rachis. 



12. SPHfENOPHYLLiTES. — Lcavcs vertlclllate, wedge-shaped, truncate ; ribs i-adlating, two- 

 forked.* 



13. AsTEROPHYLLiTES. — Leavcs vertlclllate, with a single rib.* 



• M. Brongniart sliows in his paper the great agreement between these two genera, and the stems of ferns, in every respect 

 excepting magnitude, and considers them as evidently owing their origin to plants of that natural order rather than to 

 the palms. 



- The stems of this genus are referable, in the opinion of M. Brongniart, to those of plants belonging to the family of 

 Lycopodiacece, notwithstanding the great difference of size between them and those of the recent plants of that natural 

 order. 



3 These stems, M. Brongniart supposes, belong rather to plants of the natural order of Aroidece, than to the EuphorhiactcB, 

 or to the Palms to which they have been ascribed by other authors. 



' M. Brongniart considers these to belong to some extinct genus of plants, allied to, although perfectly distinct from, the 

 recent genus Marsilea. 



' These the author thinks are the remains of an extinct genus of plants. 



