120 



MEDULLOSEAE 



[CH. 



an inner flesh. Transverse sections show that the sclerotesta 

 has three sharp longitudinal keels with corresponding furrows 

 on the inner face, and between each pair of main ribs are 2 — 3 

 less prominent ridges, usually 12 in all (fig. 426). The sarcotesta 

 consists of thin-walled parenchyma passing externally into a 



1. 



Tig. 424. Trigonocarpws. 1. Section of imperfect seed showing a mioropyle; 

 b, sclerotesta; c, cast of seed-cavity; 2, 3, apical and basal view 

 of seed-cast. (Approximately nat. size.) M. S. 



Fig. 425. Trigonocarpus Parhinsoni. 



A. Impression showing the nucule and sarcotesta. (= CarpoUthes 



alata Lind. and Hutt.) 



B. Specimen with long micropyle. (A, nat. size; from the Lower 



Coal Measures of Kilmarnock; B, nat. size; Middle C. M. of 

 Yorkshire. Kidston Coll., 1579 and 1062.) 



