68 PEOIOPIEKIS. 



Genus PROTOPTERIS, Presl. 

 [Sternberg, Flora der Vorwelt, Heft vii. 1838, p. 169.] 



This generic name was applied by Presl to a tree-fern stem 

 which he had previously figured and described as Lepidodendron 

 punotatum ; the plants which he included under Protopteris are 

 compared to living members of the Cyatheaeea. 



In Corda's "Flora der Yorwelt" eight genera, including Pro- 

 topteris and Tempskya, are grouped together in the family 

 ProtopteridecB. 



The genus Protopteris is thus defined by Corda, who consider- 

 ably extends the earlier definition in Sternberg's work' : — 



" Caudex arboreus, extus nudus vel radicuHs adventivis 

 involutus. Cortex pulvinulis foliorum quaternariis spiraliter 

 positis oblongis omata; cicatricibus foliorum medio depressis, 

 fasciculo vasorum centrali simpHci hippocrepico oontinuo decoratis, 

 et infra fasciculis rotundis minutis disjunctis 6 vel 8, et supra 

 fasciculis aequalibus lateralibus vel nullis ciroumdatis. Badiculae 

 adventivse per totam superficiem distributae. Cortex meduUosa. 



Cylindrus lignosus clausus octangularis, angulis rotundatis. 

 Liber externus in fasciculis ansaeformibus disjunctis distributus, 

 internuB continuus ligno adnatus. Vagina vasorum tenuis. 

 Lignum tenue, radiis medullaribus tenuibus vel nullis percursum ; 

 vasis amplis sexangularibus scalarseformibus. Medulla centralis 

 ampla, parenchymatosa." 



The most readily recognized characteristic of the genus is the 

 horse-shoe form of the leaf-trace, as seen on the surface of the 

 petiole scars. Schenk points out that such a character as this 

 cannot be regarded as very reliable in the determination of tree- 

 fern stems'; but, failing more trustworthy evidence, the pattern 

 of the leaf-trace is certainly a very convenient feature in the 

 identification of fossil forms. Carruthers,' in his paper on a 

 Lower Grreensand Protopteris stem, is disposed to agree with 

 Brongniart and Goppert in attaching considerable importance to 

 the form of the petiole bundle. 



' Flor. Vorwelt, p. 76. 



' Foss. Pflanz. p. 46. 



3 Geol. Mag. 1865, p. 484. 



