268 Palaeontoloffie. 



te^ 



ded on a solid parenchymatous tissue, and in which the prothallus 

 is often more or less perfectly preserved, and even the archegonia 

 can sometimes be distinguished. The structure of SpenceriteSy Sigil- 

 lariostrohiis ^ and the two seed-like fructifications Lepidocarpoii and 

 Miadesniia is briefly described. 



The systematic position of the Lycopsida is discussed, especially 

 as to whether the classes here grouped under this term, are more 

 nearly related among themselves than to out-Iying families of 

 plants. So far as the Sphenophyllales and Equisetales are con- 

 cerned, the affinities are clear. In certain respects the Psilotales 

 tend to connect the Sphenophyllales with the Lycopods, for while 

 anatomy and morphology alike indicate a nearer affinity with the 

 former, some relation to the latter may no doubt be traced in the 

 anatomy and habit. In spite of this, the Lycopodiales remain a very 

 isolated class, and though some connection with the ancient phylum 

 represented by the Sphenophyllales appears probable, the common 

 stock must lie very far back. 



Passing to the Pteropsida, and the class Filicales, the author 

 gives a rather füll account of the Botryopterideae, including a brief 

 mention of a new genus Botrychioxylon, with secondary wood, and 

 an especially important section is devoted to 'other Primofilices'. 

 Among the latter, the new name Pteridotheca is proposed for pe- 

 trified fern-sporangia of Palaeozoic age, whose precise attribution is 

 unknown. P. WilUamsoni and Stmiropteris oldhmnia are fully de- 

 scribed and illiistrated as typical examples. 



The evidence for the occurrence of Palaeozoic Marattiaceae is 

 discussed, with the conclusion that for the present we must con- 

 tinue to accept the existence of a certain number of Marattiaceous 

 Ferns, especially in the later Carboniferous and Permian periods, 

 though w^e may not always be able to distinguish their fructifications 

 from the pollen-bearing organs of Fern-like seed-plants. 



The Pteridospermeae are next considered, and the description 

 given of the Lyginodendreae, the Neuropter'idae and other members 

 of this group, with their fructifications, recently discovered, is a 

 fairly füll one, and is well illustrated. 



The systematic position of the Pteridospermeae is discussed 

 with the conclusion that, at least for the present, they should be 

 kept apart as a sub-kingdom of their own, and not included under 

 Gymnosperms. The group is provisionally diagnosed as follows: — 

 Male and female sporophylls little differentiated from the vegetative 

 foliage; no cones formf^^d. Anatomy of either stem, or leaf, or 

 both, of a Filicinean type, as was also the habit. As regards the 

 relationship of the Pteridospermeae to the Cryptogams, all the evi- 

 dence points to their having Sprung from the same stock as the Ferns. 



The relations of the Pteridospermeae to the Cj^cadophyta on 

 the one hand, and to the Cordaiteae on the other, is dealt with 

 rather fully. As regards the former group, ihe author concludes 

 that the Trigonocarpo)i type of seed is nearer to that of recent Cy- 

 cads than any member of the Lagenostonia group. It is extremely 

 unlikely that any of the direct ancestors, either of the Cycadaceae 

 or other Cycadophyta, have as yet come under Observation, but it 

 is quite conceivable that one or other line of Cycadean descent 

 may have passed through a stage not unlike that represented by 

 the Neuropteridae, though probablj^ without the polystelic modifi- 

 cation of the stem, often, but not always, found in that group. 



There are also clear indications of affinity between Pterido- 



