543 STUDIES IN FOSSIL BOTANY 



or sclerotesta, was hard and Hgnified. M. Renault 

 regarded the two layers of the testa as having been 

 derived from two integuments, a view which he 

 believed to be supported by the structure of the ovule, 

 as above described. There is, in fact, the same doubt 

 here as in the case of recent Cycadaceous seeds, in 

 which some botanists regard the double testa as 

 representing two integuments, while others consider 

 that a single integument has undergone differentiation 

 into distinct layers. 



The vascular bundle which enters the chalaza gives 

 off branches, both into the testa and into the nucellus ; 

 the former traverse the inner part of the sarcotesta, 

 a single or double bundle running up on each side of 

 the seed, just outside the lateral edges of the sclerotesta 

 (cf. Rhabdocarpus, Fig. 185), while the latter enter the 

 nucellus and apply themselves to the membrane of 

 the embryo-sac. At its micropylar end, the nucellus, 

 which was probably free from the integument, contains 

 a pollen-chamber, provided with a neck, which projects 

 into the micropyle. Apart from its bilateral symmetry, 

 the seed agrees very nearly in structure with the 

 Trigonocarpus type, described on p. 452. In certain 

 species of Cordaicarpus the archegonia have been 

 found. They occur in the usual position, at the upper 

 end of the endosperm, and two of them are shown in 

 a longitudinal section of the seed. 



Our illustration, Fig. 198, is from a seed which M. 

 Renault separated generically from Cordaicarpus, on 

 account of the distribution of the vascular bundles. 

 In Cycadinocarpus, as the new genus is named, the 

 inner vascular system follows the endotesta, and does 



