MESOZOIC PLANTS PERU 53 



The reflexed basal pinnules figured by Zeiller in material 

 from Pinonate were observed in several specimens from San 

 Lorenzo where the impressions are of the upper side of the 

 frond. Where the opposite surface is preserved the rachis 

 entirely obscures this arrangement. From the large amount 

 of material from Peru that I have seen it seems probable 

 that this reflexion of the basal pinnules of the ultimate pin- 

 nae is a constant feature. 



The pinnae in the South American form are not inclined 

 to the rachis and if the venation of a pinnule from Bernissart, 

 Belgium figured by Seward actually depicts the course of the 

 veins, it is considerably different from what obtains in 

 Weichselia peruviana. There is also considerable difference 

 of opinion regarding the specific identity of the European 

 material referred to Weichselia reticulata, both Nathorst 

 and Gothan differing from Seward in his treatment of this 

 form. 



There is also some difference of opinion as to the botanical 

 position and habit of Weichselia. Bommer considers the 

 pinnae to have been palmate which is not borne out by the 

 South American material. Gothan suggested a dune habi- 

 tat, I suspect because of the frequent occurrence of the Euro- 

 pean form in sandstones. The South American species is 

 excessively abundant and is almost invariably found in shales 

 and these are often in a non-sandy region where there is no 

 lithologic evidence of dune structures, or any probability 

 that dunes had ever been present. 



Weichselia reficulata has been recorded in Europe and 

 Asia from a number of horizons ranging in age from the 

 Purbeckian to the Senonian, and is not, as at present under- 

 stood, any more characteristic of Neocomian time than it 

 is of Barremian or Apiian time. 



The genus is curiously absent from the Mesozoic floras of 

 North America, only one occurrence, namely in the Black 

 Hills, being known, and it is by no means certain that these 

 scraps from the Fuson formation of eastern Wyoming really 



