346 SEQTJOIINEAE [CH. 



Further light will no doubt be thrown on the nature of Frene- 

 lopsis when the results of the investigations of Hollick and Jeffrey 

 are published: it may be that Heer was correct in his attribution 

 of the Portuguese specimens to the Gnetales though in the habit 

 of the branching, especially in F. ramosissima, aad in the structure 

 of the stomata there is a closer resemblance to recent Callitrineae 

 than to any other plants. The genus ranges from Wealden to 

 Cenomanian rocks. 



Sequoiineae. 



In view of the restricted range of the two surviving species of 

 Sequoia and the peculiarities of the genus, to which expression is 

 given by the institution of the family-name Sequoiineae^, the 

 question of geological antiquity and past distribution assumes a 

 special interest. Reference has already been made to fossil wood 

 presenting features now found in Sequoia, but it is very doubtful 

 if the anatomical characters of the recent species are sufficiently 

 well defined to enable us to discriminatfe between the wood of 

 Sequoia and certain other Conifers. Many of the impressions of 

 vegetative shoots and cones described as Sequoia from Jurassic 

 and especially Lower Cretaceous strata do not bear a close scrutiny. 

 The widely spread species often referred to as Sequoia Reichen- 

 bachii affords no real evidence of affinity to the recent genus and 

 the same remark applies to specimens included in Heer's genus 

 Sphenolepidimn and compared by authors with Sequoia. Some of 

 the imperfectly preserved Jurassic cones agreeing superficially with 

 those of Sequoia may well belong to species of Sequoiineae. 



Though in the majority of instances Jurassic and Cretaceous 

 records do not prove the former presence of Sequoia or a closely 

 allied type, some of them afford justification for the belief that the 

 American trees are survivals from at least the later floras of the 

 Mesozoic era. On the other hand Tertiary strata in many parts of 

 the world supply clear evidence of the wide distribution of Sequoia 

 or some nearly related Conifers in Europe and elsewhere^. The 

 inference suggested is that the recent species survive in Cahfornia 

 because of the greater possibilities of migration towards the more 



' See page 151. 



2 Mr E. W. Berry (16) has recently published a sketch-map illustrating the world- 

 wide distribution of fossils referred to Sequoia. 



