CORDAITEAE 551 



belonging to undoubted Cordaiteae ; but this distinction 

 is no longer absolute, for, as we have seen, there are 

 stems, apparently of ■ true Cordaiteae, in which some 

 centripetal wood is present, as it is in the Poroxyleae 

 and Pityeae. In fact, on our present knowledge it is 

 impossible to draw any sharp distinction between these 

 three families, and we have therefore grouped them 

 under the common name Cordaitales. If the seeds 

 of Poroxylon are represented, as M. Grand'Eury believes, 

 by Rhabdocarpus, the very close affinity of this family 

 to true Cordaiteae is further confirmed. 



The leaves, in their general form and venation, recall 

 those of such Coniferae as Agathis, though often greatly 

 exceeding those of any known Conifer in size. 1 In 

 internal structure the leaves agree almost exactly 

 with the single pinnae of the leaf in Cycads. 



In general habit, the lofty stem, with well-marked 

 internodes, departs altogether from the ordinary 

 Cycadean type, and much more resembles that of a 

 Conifer, but, in many species, at any rate, the crown, 

 with its abundance of huge simple leaves, must have 

 presented an appearance totally unlike anything in 

 either of the recent families. 



It is to the reproductive organs — the male and 

 female fructifications and the seeds — that we naturally 

 attach the chief importance in considering the affinities 

 of the Order. It is just in these organs, however, 

 that we find the most remarkable combination of 

 characters, both such as are common to various other 

 families and such as are altogether peculiar to the 



1 In Agathis macrophylla, from the Queen Charlotte Islands, the leaves 

 attain a length of 17 cm., and a breadth of 5 cm. Seward and Ford, 

 "The Araucarieae, " Phil. Trans. Royal Soc. B, vol. 198, 1906, p. 315. 



