PODOZAMITES. 241 



s, Presl, and Z. lanceolatus, L. & H. The following is his 

 definition of the genus : — 



"Leaves pinnate; segments distant, alternate, eontraoted towards 

 the base. Veins divergent at the base of the segments, approxi- 

 mately parallel in the median and apical portions." 



The definition of Podozamites, which has been somewhat modified 

 by later writers, may be stated as follows : — 



Frond (or shoot ?) pinnate, the slender axis bears segments, 

 usually somewhat far apart and at unequal distances, which vary 

 considerably in both size and shape, from narrow linear and 

 acuminate to broadly oval and obtusely pointed segments ; the 

 segments are constricted basaUy, and traversed by numerous veins 

 divergent at the base and approximately parallel to the edges of 

 the narrower segments, but convergent in the distal portions of 

 the broader segments. The base of the petiole may be enclosed by 

 broad acuminate imbricating scale-leaves. 



It has been the custom to include this widely-spread genus in 

 the Cycadacese, but it is worthy of note that the resemblance which 

 the fronds possess to a shoot of Agathis australis, Salisb., a New 

 Zealand Conifer, renders it by no means impossible that its true 

 position is among the Coniferae. Such specimens as we possess do 

 not enable us to determine the precise manner of attachment of 

 the segments, but there are indications of a spiral phyUotaxis 

 which would afford a strong argument in favour of the relationship 

 of Podo%amites to the Coniferae. Among recent Cyoads, there are 

 species of Zamia, Cerato%ainia, Macro%amia, and Eneephalartos, 

 which closely resemble PoAozamites lanceolatus^ but in the Cycadean 

 fronds the segments are more regularly disposed than in most of 

 the examples of the fossil species. Schenk prefers the generic 

 name Zamites to Podozamites ; this author has figured a specimen 

 which bears scale-leaves at the base of the petiole,^ suggesting an 

 origin from a lateral bud such as is occasionally produced by recent 

 plants of the genus Cycas ; " the scales, as Schenk points out, may 

 be compared also with the bud-scales of AgatMs. 



Another example of Podozamites {P. lanceolatus minor ') is figured 



' Sihenk (67), pi. xxxvi. fig. 3. 



2 Loc. cit. p. 160. 



3 JS^atliorst (781), pi. xvi. figs. 10 and 10a. 



