306 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1918. 



Parapecopteris, in which each pinnule bore two continuous rows of 

 ovoid sporangia more or less united and embedded in the lamina 

 and opening by apical pores. A fourth type known as Scolecopteris 

 shows the sori in two rows and consisting of four or five long-pointed 

 pendant sporangia more or less confluent proximad, united inter- 

 nally for about one-third their length to a central stalk, suggestive of 

 the modern genera Marattia, Kaulfussia, and Angiopteris, particu- 

 larly the first. 



Other fructifications (Grand'Eurya, Dactylotheca) have par- 

 tially or entirely free exannulate sporangia. Many other supposed 

 Marattiaceous fructifications have been described from the Paleozoic 

 rocks, as, for example, Hawlea in which there is a rudimentary an- 

 nulus, Urnatopteris in which the fronds were dimorphic, Eenaultia, 

 Sphyropteris, and Discopteris. 



The Marattiales are represented in Triassic floras by numerous 

 widespread forms variously referred to the genera Marattia, Marat- 

 tiopsis, Angiopteridium, Angiopteris, Danaea, Danaeopsis, Pseudo- 

 danaeopsis, Asterotheca, Taeniopteris, and Macrotaeniopteris. They 

 occur on all the continents and make a particularly large display in 

 the late Triassic (Keuper and Rhaetic), at which time palustrine, 

 often coal-forming, conditions with apparently identical species of 

 plants occur from the Arctic to the Antarctic and from Tonkin and 

 Australia to Virginia, California, and Chile. The identity of these 

 Triassic Marattiales with existing forms rests on the form and vena- 

 tion of the fronds, the arrangement and structure of the sporangia, 

 and even the spores. 



The Marattiales were less dominant in the overlying Jurassic, and 

 they were still more reduced during the Lower Cretaceous (Angiop- 

 teridium, Nathorstia, Taeniopteris?). Nathorstia, with several 

 Greenland and Bohemian species shows pinnate fronds with narrow 

 entire pinnules bearing two rows of circular synangia of radially ar- 

 ranged sporangia united to a central receptacle. 



Subsequent to Lower Cretaceous times Marattiaceous remains are 

 infrequent, although occasionally brought to light in the Upper 

 Cretaceous and Tertiary. A Marattia is described from the English 

 Eocene and a second from the French Oligocene. 



The order Osmundales includes the two recent genera Osmund a 

 and Todea. together with a dozen or 15 species with large sporangia 

 arranged in small groups, in linear and often confluent sori, or clus- 

 tered around the axis of the much reduced fertile pinnae. An annulus 

 is represented by a group of thick-walled cells below the apex. These 

 stand somewhat apart from the balance of existing ferns and are 

 wide-ranging forms, some of which are found on all the continents, 

 Osmunda being cosmopolitan and Todea antipodean. Aside from 



