364 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



Only a summary of the geological history of the order can be given 

 in the following paragraphs. Petrified wood from the Paleozoic 

 can not be accepted as an indication of the presence of this order, 

 since the wood anatomy is practically indistinguishable from that 

 of the Cordaitales, hence the term Araucarioxylon may be of a dual 

 significance. The Upper Carboniferous and Permian genus Walchia 

 had foliage like that of the modern acicular-leafed Araucaria, bossed 

 pith casts caused by the interlaced sclerenchyma fibers at the periph- 

 ery of the pith, spirally-arranged leaf cushions, araucarian wood 

 anatomy and single-seeded cone scales, and is commonly regarded as 

 an early member of this order, as is also the Carboniferous genus 

 Schizodcndron (Tylodendron), and the Permian genera Gomphos- 

 trobus and Ulmannia. Permian leafy twigs have been referred to the 

 genus Araucarites and various older Mesozoic genera, such as Al- 

 bertia and Pagiophyllum probably belong in this alliance. Un- 

 doubted Araucarian wood and single-seeded cone scales are cosmo- 

 politan during the Jurassic, and continue unabated throughout the 

 Lower and Upper Cretaceous. Dammara foliage and cone scales like- 

 wise become cosmopolitan during the Upper Cretaceous, and extinct 

 genera such as Pseudoaraucaria, with two seeded sporophylls, and 

 Protodammara, with three seeded sporophylls, have also been de- 

 scribed. The order appears to have continued its world-wide range 

 well into the Tertiary for unquestionable araucarian remains of this 

 age have been recorded from the New Siberian Islands north of Asia, 

 North and South America, Europe, East India, on the border of 

 the Antarctic. Africa, then as now, is without records. That the 

 Araucariales began to dwindle in the late Tertiary and during the 

 Pleistocene is shown by their absence at those times throughout the 

 Northern Hemisphere, their presence on Kerguelen Island and in 

 the Pleistocene of the Falkland Islands, and their subfossil occur- 

 rence beyond the present range of the existing species. 



The Coni ferales as here understood is an order coterminous with 

 the family Pinaceae of the older botanists, and Mould possibly be 

 more appropriately termed the Pinales. The details of structure 

 and distribution belong more properly to recent botany, and such 

 as are mentioned in the present connection will be introduced in the 

 brief sketch of the three families into which the order is segregated. 

 These are the Taxodiaceae, Cupressaceae, and Abietineaceae. 



The family Taxodiaceae comprises 8 existing genera and about 13 

 existing species characterized by a nearly complete coalescence of 

 bract and scale, wingless pollen, and spiral phyllotaxy. The extinct 

 species greatly outnumber the existing, and the family has evidently 

 passed its climacteric stage and seems destined to extinction. More- 

 over, none of the genera has more than three existing species (Ath- 

 rotaxis), three have but two (Sequoia, Taxodium, Glyptostrobus), 



