XXXV] COEDAISPERMUM ; CYCLOCARPON 335 



author of the genus to Cordaites principalis but,, as Kidston has 

 pointed out, there is evidence that this correlation may be incorrect : 

 there is, however, no doubt as to its Cordaitean parentage. 

 Specimens included in this genus agree closely with species of 

 Cardiocarpus, but they are usually described as being distinguished 

 by the absence of a flat border and by a more rounded and less 

 cordate base. In the example of Cordaicarpus Cordai shown in 

 fig. 502, C, and in other species assigned by authors to this genus 

 there is a narrow border and the form of the base is an inconstant 

 character. As Kidston 1 and other authors point out, there are 

 no definite and constant characters by which to distinguish 

 Cardiocarpus from Cordaicarpus as regards the form of the seeds 

 preserved as casts or impressions. A further account of Cordai- 

 carpus is given on a later page. 



Cordaispermum. This designation was formerly adopted by 

 Eenault 2 for seeds having the form and anatomical features 

 of Cardiocarpus which there is good reason for attributing 

 to Cordaites or to some allied genus. In view of the fact 

 that the majority of the seeds under consideration are un- 

 doubtedly Cordaitean there is no need to employ this additional 

 generic name. 



Cyclocarpon. Fiedler 3 instituted this term for seeds previously 

 described by Berger as Cardiocarpon emarginatum (fig. 502, B, 

 now included in Samaropsis) and added a new species Cyclocarpon 

 nummularium. Brongniart 4 subsequently described the structure 

 of two species, C. tenue and C. nummulare, which he referred to 

 Fiedler's genus, and Bertrand 5 has shown that these differ from 

 the genus Cardiocarpus in the recurrent course of the bundles 

 given off from the chalazal strand as in the genus Rhabdospermum 

 (cf. fig. 501, E). There are no good grounds for retaining the 

 designation Cyclocarpon for casts and impressions, as the speci- 

 mens so named are indistinguishable from impressions referred to 

 Cordaicarpus. The generic name Cyclocarpus, retained by Ber- 

 trand only for C. tennis and C. nummularis simply for anatomical 

 reasons, is now altered to Cyclospermum on the ground that the 



1 Kidston (94) B. p. 263. 2 Renault (80 2 ), p. 102. 



3 Fiedler (57) p. 291. 4 Brongniart (81) Pis. iv., v. 



6 Bertrand, C. E. (08 2 ). 



