330 



TRIGONOCARPALES 



[dn. 



though relatively more prominent, is comparable with that in 

 StepTianospermum, while the basal chamber recalls that in the 

 seed named by Scott and Maslen Trigonocarpus Oliveri 1 but 

 subsequently removed by Salisbury 2 from that genus. There is 

 no evidence as to the parent-plant of Polylophospermum, but it 

 may be assumed to have been a Pteridosperm, probably one of 

 the Medulloseae. 



Codonospermum 3 . Brongniart. 



Our knowledge of this peculiar genus is derived from Brong- 

 niart's description of the type-species Codonospermum anomalum* 

 (fig. 506, B, C) from St fitienne and from Kenault's account of 

 C. olivaeforme 5 . The seeds are globular or ellipsoidal and reach 

 a length of 2 cm. : the testa is differentiated into an outer flesh 



FIG. 498. A, B, Codonospermum. A, C. olivaeforme, longitudinal section showing 

 the seed-proper and the air-chamber, s; pc, pollen-chamber. B, Diagram- 

 matic sketch of a Codonospermum showing the vascular supply, v, and the 

 fibrous arcs, /, in the wall of the lower part of the seed. C, Aetheotesta elliptica, 

 s, sarcotesta with lacunae; v, vascular supply. (After Renault.) 



and a sclerotesta and has usually eight ribs. The most striking 

 feature is the division of the seed into two regions, an upper portion 

 containing the nucellus and megaspore and a lower portion in 

 the form of an empty chamber that probably served as a float 



1 Scott and Maslen (07) PI. xra. fig. 19. 



2 Salisbury (14). 8 Ktidwv, a bell. 



4 Brongniart (74) p. 257, PL xxni. figs. 9-12; (81) p. 28, PL C, figs. 9-12. 

 6 Renault (93) A. PL LXXXVII. ; (96) A. p. 393. 



