386 E. A. Newell Arher — Homoeomorphy in Fossil Plants. 



in habit to Neuropteris gigantea, Brong., and Z. German (Giebel) 

 to iV. Jieterophylla, Brong. The question arises how far the presence 

 or absence of a single character, such as the anastomosis of the 

 secondary nerves, should be regarded as of systematic value. 



To take another illustration. In the Permo-Carboniferous rooks 

 of India and the Southern Hemisphere there occur an abundance of 

 fronds of two genera, Glossopteris and Qangamopteris. According 

 to our present knowledge, the latter differs from the former, at least 

 in the commoner species, only in the absence of a midrib, a character 

 which we also know is not present in all fronds of undoubted 

 Glossopterids.^ Etheridge ^ has pointed out how closely certain 

 fronds of these two genera resemble one another. What weight 

 should therefore be given to a single point of difference, such as 

 the presence or absence of a midrib ? 



Often also plants from widely separated areas, which may or may 

 not be contemporaneous, bear a close resemblance to one another, 

 although definite characters may exist which clearly distinguish them. 

 This is the case with Aneimites ovata (McCoy) from Arowa, New 

 South Wales (? Carboniferous), which so closely resembles Bhacopteris 

 incequilatera (Goepp.), a well-known British Lower Carboniferous 

 plant, that it is a matter of dispute whether the two are not 

 identical.^ 



Many other instances might be quoted. In Dictyozamites, a Lower 

 Oolite genus recently described from Britain for the first time by 

 Mr. Seward,* we have an interesting case of parallelism with 

 Otozamites. Professor Zeiller ^ has also recently pointed out that the 

 genus BMptozamites of Schmalhausen represented in the Permian of 

 Eussia may eventually prove to be distinct from the Noeggerathiopsis 

 of Gondwana-land, which it so closely resembles. 



These are illustrations of a common difficulty constantly present 

 in palgeobotanical study. Before further light is thrown on the 

 affinities of such plants by the discovery of their fructifications, 

 discoveries which will often in themselves remove the difficulty, 

 it would appear that any help which can be given as to the meaning 

 of these similarities of habit would be welcome. Such guidance 

 may, I think, be found in recent progress in other branches of 

 palaeontology, especially in the elucidation of the Ehabdophora and 

 the Jurassic Brachiopoda. 



In an interesting paper published in the Quarterly Journal in 

 1895, Mr. S. S. Buckman ^ pointed out that in the Jurassic 

 Brachiopods, and also to some extent in the Ammonoidea, close 

 resemblances occur between species of different origin and descent. 



1 Zeiller, Bull. Soc. geol. France, ser. iii, vol. xxiv (1896) ; Seward, Q.J.G.S., 

 vol. liii (1897), p. 318 ; Arber, Q.J.G.S., vol. Iviii (1902), p. 9. 



2 Etheridge, jim. : Proc. Linn. Soc. N.S. Wales, ser. ii, vol. ix (1894), pp. 240-1. 



3 Arber, ibid., p. 21 ; Kurtz, Q.J.G.S., vol. lix (1903), pp. 26 and 28. 

 * Seward: Q.J.G.S., vol. lix (1903), p. 217. 



5 Zeiller: Compt. rendu Acad. Sci., t. cxxxiv (1902), pp. 887-891. 

 ^ S. S. Buckman, "The Bajocian of the Mid-Cotteswolds," Appendix, 'Note 

 on certain Brachiopoda' : Quart. Journ. Geol. Soc, vol. li (1895), p. 456. 



