CONIFERAE 605 



imperfect, so that Coniferous remains, though abundant 

 enough, have been spoken of as among the most 

 unsatisfactory objects with which the palaeobotanist 

 has to deal. Of late years some real advance has been 

 made, but the Coniferae are still, in the present state 

 of our knowledge, unsuited for full treatment in the 

 present course, the object of which is to bring forward 

 only the best-ascertained results in our subject. One 

 or two points, however, may be briefly referred to. 



The Coniferae are evidently of great antiquity, for 

 remains which can only be referred to this Order have 

 been found with certainty in the Permian and possibly 

 in earlier Palaeozoic strata. An interesting Permian 

 genus, unfortunately still imperfectly known, is Walchia, 

 leafy twigs of which are common fossils, while some 

 specimens have been found in fruit. The habit of 

 these branches, of which several species have been 

 described, is quite like that of some of the recent 

 Araucarias, such as the Norfolk Island Pine, A. excelsa. 

 Certain curious fossils, long described as a distinct 

 genus, under the name of Tylodendron or Schizodendron, 

 have turned out to be casts of the medullary cavity 

 of stems, probably identical with those of Walchia, to 

 which they would thus stand in precisely the same 

 relation as that of the Sternbergia casts to the stem 

 of Cordaites. The casts are marked with a characteristic 

 areolation, corresponding to the course of the primary 

 vascular bundles, and agree wonderfully closely with 

 the configuration of the pith in the recent genus 

 Araucaria. The structure of the wood, surrounding 

 the pith of Tylodendron, is sometimes preserved, and 

 is found to be of an Araucarioxylon type, known as 



