micropylar tube a seed of _Encephalartos Lehmanni_ presents a fairly close resemblance to a _Trigonocarpus_. Salisbury has pointed out that the three species _T. Parkinsoni_, _T. shorensis_, _T. pusillus_ form a consecutive series illustrating the gradual disappearance of the secondary ribs that form a prominent feature in _T. Parkinsoni_; but for a comparison of these with other types of fossil and recent seeds the reader is referred to Salisbury’s summary[858]. =Tripterospermum.= Brongniart. The seed on which this genus was founded by Brongniart[859] is clearly very closely related to _Trigonocarpus_ and, as Oliver[860] says, the distinguishing character described by the author of the genus is unimportant. Brongniart describes the type species, _T. rostratum_, as characterised by the presence of three prominent wings composed of a testa differentiated into an inner hard tissue and an outer lacunar tissue. It is, however, hardly possible to say whether the outer soft tissue was originally flattened in the form of ‘wings’ or pressed down on to the harder shell. Renault[861] notes the association of seeds that he refers to this genus with the leaves of _Dorycordaites_, but apart from the improbability of any connexion between _Tripterospermum_ and _Cordaites_, Renault’s seeds are too imperfect to demonstrate their identity with Brongniart’s genus. Kidston[862] has described an impression of a three-winged seed from the coal-field of Staffordshire as _Tripterospermum ellipticum_, a form described on page 357 as _Polypterocarpus anglicus_ (fig. 496, B). =Ptychotesta.= Brongniart. The type-species of this genus[863], _Ptychotesta tenuis_[864], about 3 cm. long, is characterised by six very prominent flanges or wings formed by the fissured or folded sclerotesta (fig. 495, B). There is no information as to the vascular supply or other anatomical details. It is not at all improbable that there is no real distinction between this genus and Brongniart’s genus _Hexapterospermum_. =Hexapterospermum.= Brongniart.