120 CORDAITEAE. 



testa has six wing-like duplications of the testa. The seeds of Eriotesta 

 and Codonospermum have eight of these marginal projections. Eriotesta is 

 further distinguished by the nature of the surface of the testa, which is 

 entirely covered with close-set hair-like fibres swelling into a knob at the 

 apex. But the most remarkable form is seen in Codonospermum. The 

 seed, which is depressed in the direction of the axis and has flat edges, has 

 a wing like a circular collar on the margin of the flat basal surface, and in 

 the same manner the entering vascular bundle is enclosed for some distance 

 in a tube-like process of the testa. 



I do not venture to decide how far the genera described by Williamson 1 

 coincide with those of Brongniart, though from the details of their internal 

 structure they may all be supposed to belong to the same group. They are 

 described under the names Cardiocarpon, Trigonocarpon, Malacotesta, 

 Lagenostoma, and Conostoma. Williamson agrees with Brongniart in 

 speaking of the boundary-line of the nucellus in all cases as the ' nucular 

 membrane,' and of the boundary of the embryo-sac as the 'perispermic 

 membrane.' In some forms, Lagenostoma for example, in which the apex 

 of the nucellus in the region of the pollen-chamber is split into two tissue- 

 layers, the outer of these which is plicately sinuous is termed the ' canopy.' 

 The seed described by Hooker and Binney 2 has been again found by 

 Williamson and figured as Trigonocarpon olivaeforme. In the transverse 

 section it shows the character of Tripterospermum, Brongn., but with 

 the difference that it has three slightly raised secondary ribs on each 

 of the surfaces between the three wing-like projections. The beak-like 

 apex which is pierced by the micropylar canal is formed entirely of the hard 

 layer of the testa. It is a question whether the casts described by Heer 3 as 

 Rhynchogonium do not belong to this form. The genus Malacotesta, of 

 which only one seed has been examined, seems to have had a single fleshy 

 membrane and no hard endotesta. 



Lastly, Dawson 4 has sought to class with Brongniart's genus Aetheo- 

 testa certain fossils which have been found in England in the Upper 

 Llandovery and Ludlow beds and in the Devonian formation of New 

 Brunswick. These were first described and named Pachytheca by Hooker 6 , 

 who inclined to regard them as fructifications of Lycopodinae. But they 

 have nothing whatever to do with Aetheotesta or with any seed of Gym- 

 nosperms, as I have learnt from examination of specimens and sections, and 

 therefore we cannot with Dawson appeal to them to show that Nemato- 

 phycus Logani, which occurs with them, is a Conifer. They are small 

 spheroidal smooth bodies of an intense chestnut-brown colour and of differ- 

 ent sizes ; they are hollow in the centre, and the thick wall of the cavity 



1 Williamson ',!), vin. a Hooker and Binney (1). 3 Heer (5), vol. 41, t. 5. * Dawson (1), 

 p. 108; also (3 X and (4), p. 306. 3 Hooker (2) ; see also Etheridge in Hicks (i). 



