216 MR R. KIDSTON AND MR D. T. GWYNNE-VAUGHAN ON 



Eichwald, believing that his stem was generically identical with that described by 

 Brongniaut, and for which Corda founded the genus Sphallopteris, adds to the 

 original characters some which are derived from the internal structure of the stem. 



One of the chief distinctive differences which separates Chelepteris from Spthallo- 

 pteris, as pointed out by Eichwald, is the smaller vascular axis of the latter when 

 compared with that of the former. 



Bathypteris, Eichwald. 



1860. Bathypteris, Eichwald, Lethsea Rossica, vol. i., p. 96.] 



Stem large, simple, almost cylindrical, swollen at the middle, and contracted 

 towards the extremities ; the surface is composed of contiguous petiolar bases, discs 

 ( = broken-over surface of petioles) much sunk in, almost round or somewhat squared, 

 provided in the centre with a small semicircular cicatrice ; the margins of the petiole 

 bases only are prominent and riddled ivith holes or canals arising from the adven- 

 titious roots ; the elongated leaves, closely placed beside each other, are fixed at the 

 upper extremity of the stem. 



This genus is said to differ from Chelepteris and Sphallopteris in the petiole bases 

 being scarcely visible at the surface of the stem, whereas in Chelepteris and Sphallo- 

 pteris the stems possess prominent petiole bases. It will be seen as we proceed that 

 this character depends on the state of preservation of the specimens. The stele of 

 Bathypteris was not preserved. 



Anomorrhcea, Eichwald. 



I860. Anomorrhoea, Eichwald, Lethxa Rossica, vol. i., p. 102. 



Stem fairly large and composed of the bases of almost rhomboidal-tubidar petioles 

 which are provided with many layers, ascending obliquely and placed quincuncially. 

 They enlarge insensibly towards the extremity and are provided with a semicircular 

 vascular bundle, sometimes in the form of a horse-shoe, of which the centre is hollow ; 

 the interpetiolar interstices have no adventitious roots, by which the genus is princi- 

 pally distinguished from the genera mentioned, above* 



The stele was not preserved. 



Eichwald was mistaken in supposing that Anomorrhoea did not possess adven- 

 titious roots, for sections of the specimen show them to be present as in all the other 

 three genera to which reference has been made. 



These four genera have been differently regarded by subsequent writers, but it 

 must be borne in mind that probably all those authors who have referred to them had 

 only the descriptions and figures for their guidance, for it is certain that no micro- 

 scopical preparations were made from the specimens at the time they wrote, and it is 

 also further highly probable that they were unable to examine the original types. 

 * The genera referred to by Eichwald are Sphallopteris, Bathypteris, Chelepteris, and Desmia. 





