GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION 635 



distinguishable from the living genera. Fossil sporophylls exactly 

 like those of Cycas have been found, and forms resembling closely 

 Zamia and other living genera, occur. Others of the fossil Cycads, 

 however, especially the Bennettiteae, differ very much from any 

 existing genera. 



Coniferae. The Conif erae, at present the predominant type of 

 Gymnosperms, can be traced back to the later Palaeozoic, certain 

 Permian fossils being probably true Conifers, although the remains of 

 those early types are not well preserved. The Permian genus Wal- 

 chia is said to present features resembling the living genus Araucaria. 



Another Permian genus, Voltzia, has been referred to the Taxodi- 

 neae, which includes the Sequoias and Bald-cypress (Taxodium). 

 Both of the latter genera occur abundantly in a fossil state from 

 the lower Cretaceous upward, and were evidently far more widely 

 distributed than at present, the same being true with some other 

 genera e.g. Glyptostrobus, Cryptomeria, etc. Some of these fossils 

 are not to be distinguished from living species. 



The Cypresses (Cupressineae) are first met with somewhat later 

 than the Taxodineae. 



Taxaceae. The Yew family is less abundantly represented in a 

 fossil state, but there are remains which can be referred to most of 

 the living genera. Torreya, now represented by four widely scat- 

 tered species, appears first in the lower Cretaceous, and the genus 

 Cephalotaxus occurs in the same formation. Phyllocladus and Podo- 

 carpus have also been found in Cretaceous formations. 



Pinaceae. The bulk of the living Conifers belong to the Pinaceae. 

 which comprise the Pines, Firs, Spruces, etc. Fossils resembling 

 these have been described from the Permian, but it is not until the 

 lower Cretaceous that cones of unmistakable Pinaceae are encoun- 

 tered. Here are found numerous cones referable to the living genera 

 Pinus, Cedrus, Abies, Tsuga, and others. 



In the Tertiary the Conifers increase in importance, and some of 

 the living genera which are now of very restricted range, like the 

 genus Sequoia and Taxodium, were then widely distributed, as is 

 testified by their fossil remains. 



Gnetales. The third class of living Gymnosperms, the Gnetales, 

 is so scantily represented in a fossil state as to throw no light upon 

 the history of these peculiar plants. 



Fossil Angiosperms 



There is much doubt as to the time of the first appearance of Angio- 

 sperms, their fossil remains in the earlier formations being too 

 meagre and imperfect to make their nature certain. Many fossils 

 formerly considered to be Angiosperms are now known to belong to 



