PALEOBOTANY BERRY. 393 



teris, Matonidum) of the family Matoniaceae, a family with but two 

 existing- Malayan species of Matonia. 



There were several wide-ranging Jurassic species of Laccopteris 

 and Matonidium, characterized by pedate fronds somewhat similar 

 to those of the Dipteriaceae, but less variable or striking. The 

 Gleicheniaceae were sparingly represented by species of Gleichenia : 

 the Osmundaceae by Osmundites; the Schizaeaceae by Klukia; the 

 Cyatheaceae by Dicksonites and Coniopteris; the Polypodiaceae by 

 Cladophlebis, Onychiopsis, and Dryopterites ; and the Hydropterales 

 by various species of Sagenopteris. Probably the most characteristic 

 Jurassic fern genera were Coniopteris, Laccopteris, and Thinnfeldia. 



No Pteridospermophytes are known as late as the Jurassic, and it 

 seems a reasonable assumption that this phylum had become extinct, 

 although Glossopteris, a possible seed fern, is recorded from the Lias 

 or basal Jurassic of southern Mexico. The Arthrophyte and Lepido- 

 phyte phyla, so prominent in the Paleozoic, had, by Jurassic times, 

 come to be represented mainly by modern-looking species of Equise- 

 tum (Equisetites), Lycopoclites, and Selaginellites. 



Perhaps the most prominent element in Jurassic floras was the 

 variety of ubiquitous genera of cycad-like fronds and fructifications. 

 These are found from the Arctic to the Antarctic and on all of the 

 continents at that time, and embrace a large number of form genera. 

 The bulk of these belong to the order TVilliamsoniales, although 

 Cycas-like fructifications are known (Cycadospadix). There is little 

 evidence of the presence of the Cycadeoidales during the Jurassic, 

 although their widespread occurrence in Lower Cretaceous times 

 indicates that they were already in existence, as does the close ap- 

 proximation to their fructifications of those of Williamsonia. These 

 have already been described in the paragraphs devoted to the Cyca- 

 dophyta. Frond genera characteristic of Jurassic rocks, and often 

 beautifully preserved as impressions, are Podozamites, Ptilozamites, 

 Pseudoctenis, Ctenophyllum, Ctenis, Taeniopteris, Nilssonia, Anomo- 

 zamites, Dictyozamites, Glossozamites, Otozamites, Pterophyllum, 

 Ptilophyllum, and Zamites. 



The remainder of the known Jurassic flora consisted of representa- 

 tives of the Coniferophytes — the most advanced phylum, the Angio- 

 spermophyta, not being certainly known earlier than the Lower 

 Cretaceous. Among the Coniferophytes, species of Ginkgo and of 

 the allied genus Baiera were perhaps the most abundant and wide- 

 spread. Jurassic Gnetales are not certainly known and the mainly 

 Paleozoic Cordaitalean order appears to have already become extinct. 

 The Araucariales were prominent throughout the Jurassic, in the 

 deposits of which age, petrified wood, twigs, and single-seeded cone 

 scales, essentially like those of the existing genus Araucaria, are 

 found in abundance at widely scattered localities. 



