Mrs Arber, A note on Cardiocarpon compressum, Will. 393 



A note on Cardiocarpon compressum, Will. By Mrs E. A. 

 Newell Arber, D.Sc, Newnham College. (Communicated by 

 Mr E. A. Newell Arber.) 



[Head 7 February 1910.] 



In 1877 Williamson* described and figured a small unattached 

 winged seed showing binary symmetry, from the Lower Coal 

 Measure nodules of Oldham, which he referred to Brongniart'sf 

 genus Cardiocarpon. On account of its flattened form he gave it 

 the specific name compressum. Other Cardiocarpons had previously 

 been described from the British Coal Measures, but only their 

 external appearance was known, whereas in the new species the 

 internal structure was preserved. Williamson figured sections cut 

 from three specimens. The most characteristic feature of the seed 

 was that the testa was divisible into two very distinct layers, — 

 an exotesta of coarse parenchyma, and an endotesta of much 

 smaller cells. No further description of the internal structure of 

 Cardiocarpon compressum, or of that of any other seed showing 

 bilateral symmetry from the British palaeozoic rocks, has been 

 published since Williamson's time. The main interest of the 

 genus Cardiocarpon lies in the great probability that it repre- 

 sents the seeds of Cordaites^. The possibility is not however 

 excluded, that seeds of this type were borne by Pteridosperms, 

 for seeds of binary symmetry have been found attached to fronds 

 of Aneimites^ and Pecopteris Pluckeneti\\. The following note 

 is based on material collected by Prof. F. W. Oliver, Dr D. H. 

 Scott, and Prof. Weiss, and generously made over to the present 

 writer for examination. The material consists entirely of sections 

 of unattached seeds occurring in the " coal balls." The same 

 seed is seldom met with in more than one section. 



The contrast between exotesta and endotesta already men- 

 tioned afibrds the readiest means of identifying Cardiocarpon 

 compressum in microscopic section. There is sufficient variation 

 among the specimens, both in dimensions and structure, to suggest 

 that Cardiocarpon compressum, instead of being a single species, 

 may possibly represent an assemblage of seeds belonging to closely 



* W. C. Williamson, " On the Organisation of the Fossil Plants of the Coal- 

 measures," Pt. VIII., Phil. Trans. Boy. Soc. Vol. clxvii. Pt. i. p. 213. 



t A. Brongniart, Prodrome d\me histoire des vegetaux fossiles, Paris, 1828. 



X F. C. Grand'-Bury, Memoire sur la Flore Carbonifere du Departement de la 

 Loire, 1877, p. 233. 



§ David White, "The Seeds of Aneimites," Smithsonian Miscellaneous Collec- 

 tion, Vol. XLVii. 1905, p. 822. 



II F. C. Grand'-Eury, " Sur les graines trouvees attachees au Pecopteris Plucke- 

 neti, Schlot," Comptes Rendus, t. cxl. 1905, p. 920. 



