454 GENERA INCERTAE SEDIS [CH. 



Podozamites distans (Presl). 



This Ehaetic species 1 differs very slightly from the Jurassic 

 type Podozamites lanceolatus and there has been much confusion 

 on the part of authors between the two forms 2 which, indeed, 

 cannot always be clearly distinguished. P. distans is often repre- 

 sented only by detached leaves but in some specimens the shoot 

 reaches a length of 20 cm. The slender axis bears distant, 

 lanceolate or ovate-lanceolate leaves, sometimes slightly falcate 

 with a rounded or obtusely pointed apex and gradually contracted 

 at the base which, as Zeiller says, may assume the form of a very 

 short pedicel. The leaves may be 4 7 cm. long and 5 14 mm. 

 broad; the veins, 0-4 0-7 mm. apart, are dichotomously branched 

 in the proximal portion of the lamina but elsewhere parallel and 

 simple, except that they slightly converge at the apex. The 

 epidermal cells have straight walls and the stomata, which occur 

 on the lower surface, either in rows or scattered, are surrounded by 

 small subsidiary cells (fig. 812, E). The leaves are usually rather 

 broader in proportion to their length than those of P. lanceolatus 

 and the apex is less pointed. Braun 3 instituted two varieties , 

 longifolius and latifolius, and to these Schenk 4 added others. Th? 

 species is recorded from the Rhaetic of Scania 5 , where it is abundant, 

 from Persia 6 , Tonkin, and many other regions: it occurs also in 

 Jurassic strata 7 , but on the whole P. distans is a characteristic 

 member of Rhaetic floras. 



The Rhaetic species Podozamites Schenki Heer 8 founded on 

 Jurassic specimens from Siberia and described by Zeiller 9 and 

 Nathorst from Tonkin, Persia, and Sweden is distinguished from 

 P. distans by the smaller shoots and the more acuminate leaves. 



Podozamites lanceolatus (Lindley and Hutton). 



The type-specimen of Zamia lanceolata Lind. and Hutt. 10 in the 

 Manchester Museum from the Middle Jurassic beds of Yorkshire 

 consists of a slender axis bearing scattered and distant linear- 



1 Sternberg (38) A. PL XLI. fig. 1. 



2 See Zeiller (03) B. p. 159 for examples of P. distans referred to P. lanceolatus. 



3 Braun (47) p. 85. 4 Schenk (67) A. Pis. xxxv., xxxvi. 



5 Nathorst (78) B. Pis. xm., xv. 



6 Zeiller (03) p. 193. ' For references, see Zeiller (03) B. p. 159. 

 8 Heer (77) ii. p. 45. 9 Zeiller (03) B. PI. XLII. 



10 Lindley and Hutton (36) A. PI. xciv. 



