574 PTERIDOSPERMS, ETC. [CH, 



In certain species of Alethopteris the pinnules appear to 

 have been deciduous as in Didymochlaena among recent ferns ^. 

 A piece of cuticle from the upper surface of a pinnule of 

 Alethopteris Orandini (Brongn.) figured by Zeiller* shows very 

 clearly the polygonal form and straight walls of most of the 

 epidermal cells, those above the veins being almost rectangular. 

 The position of the sunken stomata is revealed by small circular 

 spaces surrounded by a circle of cells. 



The absence of fertile specimens of this common genus of 

 Upper Carboniferous plants led Stur^ to exclude it from the 

 ferns. Although no seeds have so far been found in organic 

 connexion with an Alethopteris frond, it is certain that some 

 species, probably all, represent the foliage of Pteridosperms. 

 Renault was the first to describe petrified specimens of Aletho- 

 pteris fronds exhibiting the anatomical structure of Myeloxylon 

 (leaf-axis of Medullosa). The calcareous nodules from English 

 Coal-seams contain numerous fragments of the Myeloxylon 

 type of rachis bearing Alethopteroid pinnules. 



The constant association of the fronds of Alethopteris 

 lonchitica and Trigonocarpon seeds noticed by Mr Hemingway 

 in the Coal-Measures of Yorkshire led him to regard the species 

 as seed-bearing : it has since been recognised as the foliage of 

 the Pteridosperm Medullosa anglica*. 



Grand'Eury° has recorded the association in French Coal- 

 fields of species of Alethopteris with Trigonocarpon and Pachy- 

 testa seeds. 



Alethopteris lonchitica (Schlotheim)®. Figs. 364, A; 290, A. 



This species, described by Schlotheim in 1820 as Filicites 

 lonchiticus and previously figured by Scheuchzer'', is abundant 

 in the Middle and Lower Coal-Measures of Britain^. It is 

 characterised by large tripinnate fronds, probably quadripinnate 

 in the lower part, bearing primary pinnae of a more or less 



1 Grand'Eury (90) A. = Zeiller (90) PI. ix. fig. 6, A. 3 §(;„, (83). 



* Scott (07) p. 206 ; Scott and Maslen (06) p. 112. 



s Grand'Eury (04). 



« For synonymy, see Kidston (03) p. 772 : Zeiller (88) A. 



' Scheuchzer (1723) A. PI. i. fig. 4. » Kidston (94) p. 245. 



