with. Exhibition of a Rare Species (Cycas Micholitzii). 303 



noticed by Moore in the Australian species Macrozamia hetero- 

 mera*, in some varieties of which the narrow pinnae may be 

 divided into six or seven ultimate segments. In the dichotomous 

 method of branching there is the closest resemblance between 

 Moore's species and Cycas Micholitzii. It is now generally ad- 

 mitted that Cycads and Ferns were probably derived from common 

 ancestors, a conclusion based in part upon certain resemblances 

 between existing members of these two groups, but founded 

 mainly on the discovery of several Palaeozoic types of a generalised 

 type in which Cycadean and Filicinean characters are intimately 

 associated. In view of this relationship it is interesting to find 

 another common feature in the dichotomous branching of the 

 pinnae. The fronds of Matonia pectinataf, as recently shown 

 by the authors of an exhaustive paper on the young plants 

 of this ancient type, exhibit both monopodial and dichotomous 

 branching. 



Similarly, Mr Boodle + speaks of the dichotomy of the primary 

 pinnae in Gleichenia as a primitive character which occurs also in 

 Lygodium. 



In Matonia sarmentosa, Baker§, the forked linear pinnae bear 

 a close resemblance to those of Cycas Micholitzii in their method 

 of branching. Numerous other instances among fossil and recent 

 plants might be quoted of the close correspondence in the pos- 

 session of dichotomously branched pinnae between Cycads and 

 Ferns. 



The discovery of a species of Cycas with dichotomously 

 branched pinnae suggests the possibility that the simple pinnate 

 type of Cycadean frond, with its unbranched pinnae, may be the 

 result of reduction from an older type characterised by the more 

 primitive dichotomous habit. 



* Moore, Journ. Proc. R. Soc. New South Wales, "Vol. xvm. 1884, p. 115. 

 Seward, The Wealden Flora, Part II. (Catalogue of the Mesozoic Plants in the 

 Department of Geology, British Museum) 1895, p. 5, pi. xiii. 



t Tansley and Lulham, Annals Botany, Vol. xix. 1905, p. 477. 



X Boodle, Annals Botany, Vol. xv. 1901, p. 705. 



§ Baker, Annals Botany, Vol. v. 1890, p. 191, pi. xiv. 



