XXVIl] TAENIOPTERIS 489 



In some cases it is practically impossible to recognise clear 

 specific distinctions between Rhaetic and Jurassic types. 



From the Damuda and Panchet series of India (Triasso- 

 Rhaetic) Feistmantel has described large sterile fronds as 

 Macrotaeniopteris Feddeni^ which reach a breadth of 20 cm.: 

 these may be compared with the Indian species Taeniopteris lata 

 Oldham^, and to T. gigantea from the Rhaetic of Franconia* 

 and Scania. A specimen of this species figured by Nathorst* 

 from Scania has a lamina 33 cm. broad. Other examples are 

 afforded by M. Wianamattae Feist.® from rocks of the same age 

 in Australia and by Taeniopteris superba Sap.® from Lower 

 Rhaetic rocks near Autun. 



From the Rhaetic of Tonkin, Zeiller records several species, 

 among which may be mentioned T. Jourdyi Zeill.^ and 

 T. spatulata MacClelland (fig. 330, B, C). Both have simple 

 fronds. Those of T. Jourdyi reach a length of 10 — 40 cm. 

 and a breadth of 10 — 70 mm.; the rachis is characterised by 

 crowded and discontinuous transverse folds, and the secondary 

 veins (35 — 50 per cm.) are usually at right angles to the rachis. 

 This Tonkin species is compared by Zeiller with the European 

 Rhaetic species T. tenuinervis Brauns. 



The polymorphism of the fronds is a striking feature : in one 

 case described by Zeiller the lamina appears to be divided into 

 segments like those characteristic of the leaf of the Cycadean 

 genus Anomozamites. It is obviously difficult in many in- 

 stances to distinguish between detached Taeniopteroid pinnae 

 of a compound frond and complete simple leaves. In some 

 compound fern ironds, as in the recent Polypodiaceous genus 

 Bidymochlaena, the pinnules are deciduous, and the same feature 

 undoubtedly characterised the fronds of many extinct species. 

 A specimen figured by Zeiller which shows several petioles of 

 T. Jourdyi attached to a thick stem' demonstrates the simple 

 nature of the leaves. In other cases, e.g. T. vittata, specimens 

 occur in which the slightly enlarged petiole-base has a clean-cut 

 surface indicating abscission from a rhizome (fig. 332). 



1 Feistmantel (81) A. Pis. xxi. A. xxii. A. = Oldham and Morris (63) p. 41. 



3 Sohenk (67) A. PI. xxviii. fig. 12. * Nathorst (78) PI. ix. 



5 Feistmantel (90) A. PI. xxvii. ' Saporta (73) A. Pis. lxi. lxii. 



' Zeiller (02) Pis. x.— xiv. p. 66. « Zeiller (02) PI. xi. fig. 4. 



