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THE AMERICAN NATURALIST [Vol. XL 



and other genera. However, no evidence in this direction is fur- 

 nished by the variations in leaf form, for with the exception of the 

 atavistic character of the seedhng leaves which appears to be a con- 

 stant feature, and the usual reduction shown bv the senescent 

 leaves, the leaf variation is entirely fortuitous, if one may use that 

 term in this sense for the result of unknown, or at least not well 

 understood morphological and physiological causes. 



The Fossil vSpecies 



That the number of fossil species of Comptonia has been multi- 

 plied beyond what the facts warrant, seems probable without any 

 very serious consideration, ^fhat we sliould have, for instance, 

 in the area of Europe, ten or a dozen Eocene, Oligocene, and 

 Miocene species seems improbable, and this off-hand conclusion is 

 borne out by an examination of the species. We find that the limits 

 of variation within a single species as conceived by the various writ- 

 ers who have studied members of this genus, judging by tlie diverse 

 forms referred to the same species, are so wide as to include in 

 almost any of the described species (so called), gicater difl'erences 

 of size, form, or venation than exist between what aiv usually 

 regarded as really valid species by the individual ainhors. In 



examine the leaves of the sole exi.iiim ^prci,.. tor cuupariM.n. The 



leaves are usually divided nearly to the rnidriu'. ' alihi.uuh the 

 sides of the lobes often overlap, giving them the aDpcarance in 

 some cases of being only slightly incise<l. Tlii> w<»ul(l he j)ar- 

 ticularly true of similarly lobed leaves preserved a^ tos-il-. The 

 leaves are progressively simj)ler toward the llr.wcr- and in the 

 seedlings, becoming merely senate (.r even entire and lanceo- 

 late (PI. 3).^^ Thus til.- juvenile and mmh-mvuI leave, are holh 



Heating many of the fossil leaves in aj)[)eaiaii( <■: iheir niargins 



On the whole I feel justified in suggesting the changes which 



