136 F1LICES. 



margin of the leaf. If they fork, which is very commonly the case, their 

 branches diverge at a very acute angle and soon become parallel to one 

 another. Oleandra, Scolopendrium, Marattia supply examples among 

 recent Ferns. The Taeniopteridae are on the whole characteristic of the 

 Mesozoic formations ; the best known forms are Taeniopteris marantacea, 

 Presl l (Danaeopsis marantacea, Schpr) from the Letten Kohl and T. Munsteri 

 from the Rhaetic beds. Both species have simply pinnate leaves of considerable 

 size. Forms with a simple lamina not pinnately divided are termed Olean- 

 dridium. A large number of simple leaves of more than usual size have 

 been described by O. Feistmantel 2 from the Lower Gondwanas (Trias) of 

 India under the name Macrotaeniopteris. Forms of this type are very rare 

 in the Palaeozoic formations, but some examples are figured in Lesquereux 3 

 (Taeniopteris Smithsii, Megalopteris). I am not indeed sure that Megalo- 

 pteris belongs to this division ; on this point the literature cited above in 

 connection with Cannophyllites should be consulted. 



In Nervatio Neuropteridis the tertiary nerves come off at an acute 

 angle, but they describe a curve convex to the midrib as they run to the 

 margin of the leaf, with which both they and any parallel ramifications 

 which may arise form nearly a right angle. If the curvature of the tertiary 

 nerves diminishes, Neuropteris may come near to Sphenopteris or Peco- 

 pteris ; on the other hand it approaches Nervatio Cyclopteridis, the next 

 type to be mentioned, and may indeed be very like it, if the median nerve 

 is only a little more strongly developed than the lateral. In practice it is 

 often difficult to distinguish it from Cyclopteris, as may be seen by 

 comparing, for example, Odontopteris obtusiloba, Naum. and Neuropteris 

 Loshii, Brongn., which are exactly alike in the form of the leaf. In 

 Schimper 4 we find Cyclopteris and Neuropteris united for this reason 

 into one family. The true Neuropteridae are entirely confined to the 

 Palaeozoic formations ; figures of characteristic forms are to be found in 

 Schimper 5 . 



Nervatio Cyclopteridis is distinguished from Nervatio Neuropteridis 

 by the absence of a median nerve. Numerous nerves of equal strength enter 

 the lamina of the leaf and bifurcate repeatedly as they run in a curve 

 which is convex towards the apex of the leaf, and at length form a right 

 angle with the margin. Various leaves of this type are found in the 

 oldest deposits along with the previously mentioned Sphenopteridae ; on 

 the whole the Cyclopteridae are less abundant in the Mesozoic formations. 

 But there are some forms belonging to the present vegetation which follow 

 this type of nervation. Various genera have been distinguished in the 



1 Schimper (1), tt. 37, 38. Pal. Ind., ser. xii. s Lesquereux (1), t. 25, f. 7, and t. 74. 



Schimper (1). Schimper (1), t. 30, ff. 11, 12, and (2), p. 116, t. 32. 



