658 MR R. KIDSTON AND MR D. T. GWYNNE-VAUGHAW ON 



Bathypteris, Eichwald. 



I860. Eichwald, Lethxa Rossica, vol. i., p. 96. 



Bathypteris rhomboidea, Kutorga, sp. 

 (Pis. VI., VII.) 



1844. Tubicaulis rhomboidalis, Kutorga (pars), Verhandl. d. miner. Gesell, zu St Petersburg, pi. i. 



fig. 6. 

 1860. Bathypteris rhomboidea, Eichwald, Lethxa Rossica, vol. i., p. 96, pi. iv. figs. 1 and 2. 

 1869. Bathypteris rhomboidea, Schimper, Traite de paleont. vegk., vol. i., p. 704. 

 1887. Bathypteris rhomboidea, Schmalhausen, " Die Pflanzenreste der Artinskisclien und Permischen 



Ablagerungen im Osten des Europaischen Russlands," Mem. du Comite geol., vol. ii. (No. 4), 



pp. 9 and 36, pi. iii. figs. 6 and 7. 



The specimen from which our material was cut is shown at fig. 4 1 , about a half 

 natural size, and is the same example as that figured by Eichwald in his Leth&a 

 Rossica, pi. iv. figs. 1 and 2. The fossil does not contain the whole stem of the 

 plant, but merely consists of a certain thickness of its outer coating of petiolar bases 

 together with a small portion of the outer region of its cortex. The fragment we 

 received was cut from the lower end of the specimen, and proved to be very imperfectly 

 preserved ; much of the mineral matter with which it has been infiltrated has been 

 subsequently removed, leaving a petrifaction that is now somewhat fragile and friable. 

 This rendered the preparation of satisfactory microscopical sections an extremely 

 difficult matter, but thanks to the great skill of Dr F. Krantz sections have been 

 prepared sufficiently intact to enable us to elucidate the chief structural points of 

 the fossil. 



In transverse sections of our material it is seen that the extreme inner margin of 

 the fossil includes a certain amount of the outer sclerotic cortex of the stem represented 

 by fragments of comparatively small- celled dark-coloured sclerenchyma, but it is so 

 much broken up and disintegrated that little can be said about the structure of this 

 region. In fact, the first tissues that are sufficiently intact to be serviceable for detailed 

 description are those of the free petioles. One of the chief characters of the fossil is 

 the looseness with which the petioles that form the coating to the stem are packed 

 together (fig. 42). They are not in any way concrescent or even closely adpressed as 

 in the previously described fossils, but they are quite free from one another, with 

 clearly defined intervening spaces. 



Another important feature of the petiolar bases of Bathypteris which distinguishes 

 it from all the other Osmundacese known to us is the fact that they are entirely devoid 

 of any stipular expansions. The transverse sections of the petioles are in fact simply 

 rhomboidal in outline, fitting into one another without being closely adpressed. 



All the leaf-traces present the typical horseshoe-shaped curve characteristic of the 

 Osmundacese, but the arrangement of the sclerenchyma in the petiole varies consider- 



