PALEOBOTANY BERRY. 333 



cuticle was dense and the stomata were confined to the two furrows 

 on the lower side which were clothed with multicellular hairs. 



The cones of Sigillaria, usually going- by the name of Sigillarios- 

 trobus, are common as impressions, but are practically unknown 

 in a petrified condition. They were often very large, being as 

 much as five or six cm. in diameter in S. nohills. They agree in 

 having long peduncles covered with needle-like bracts. The fertile 

 part bears crowded sporophylls of somewhat variable shape with 

 flexed and imbricated distal blades. The sporangia were some- 

 times attached for nearly their wmole length to the adaxial face of 

 the sporophyll, while in other cases they are thought to have been 

 at inched distally. Some cones are known to have been heterospo- 

 rous and this was probably the rule throughout the family. It was 

 formerly thought that both the Lepidodendraceae and Sigillaria- 

 ceae became extinct with the Paleozoic, but cones considered to be 

 related to the Lepidodendraceae and named Lycostrobus are re- 

 corded from the Upper Triassic (Ehaetic) of Sweden and certain 

 remains from the Lower Triassic (Bunter) of Europe, known as 

 Pleuromeia and sometimes made the type of a separate family, are 

 now believed to represent the Sigillariaceae. Pleuromeia, which, is 

 imperfectly known, is represented by stem casts of simple stems 

 nine to ten cm. in diameter, the surface covered with remote rhom- 

 boidal, Clathraria-like, leaf scars. 



Basally the stem separates into four lobes suggestive of Stigmaria 

 or Isoetes and covered with rootlet scars like those of Stigmaria. 

 Poorly preserved terminal cones of crowded imbricated sporophylls 

 are also known. The form of the stem and the growth separation of 

 the leaf scars indicate secondary thickening ; decorticated specimens 

 resemble Knorria, and the thin central cylinder all point to a close 

 affinity with the true Sigillarias. The cone genus Poecilitostachys, 

 described by Fliche from the Triassic of France, also indicates a third 

 type of the Lepidodendrales which survived the Paleozoic. 



There remain for consideration two examples which indicate that 

 some of the Lepidophytes had definitely progressed beyond hetros- 

 pory to what amounts to the acquisition of the seed habit. The first 

 of these, unfortunately designated by the preoccupied name of Lepi- 

 docarpon, comes from the lower Coal Measure of England. In 

 Lepidocarpon the cone was of the Lepidostrobus type in all its imma- 

 ture details. Only a single megaspore reached maturity in each 

 sporangium, practically filling the whole cavity, and as it matured it 

 was inclosed with a complete investment (integument or velum) which 

 grew up from the adaxial surface of the sporophyll and opened only 

 by a narrow apical micropylar slit. At maturity the whole sporophyll 

 with its integumented megasporangium w 7 as shed as a closed seed-like 

 reproductive body. 



