PALEOBOTANY BERRY. 331 



Still another type of Lepidodendron fructification was Cantheli- 

 ophorus in which the sporophylls were commonly deciduous. Each 

 sporophyll bore two large sporangia separated by a median sterile 

 plate interpreted as representing the sporangiophore of the ancestral 

 pro-Sphenophyllum stock. 



Ulodendron branches have also been formed on certain species of 

 Lepidodendron, and other Lepidodendron shoots, known as Halonia, 

 are characterized by spirally disposed scars or tubercles thought to 

 indicate the points of attachment of cone peduncles. 



The vast majority of stem impressions represent minor variations 

 of the common Lepidodendron type. In the genus Lepidophloios 

 the bolsters were very prominent and became recumbent in old age, 

 so that the normal leaf scar appears to be at the base. The Halonia 

 branches with their spirally stalked deciduous cones appertains par- 

 ticularly to Lepidophloios, which, anatomically, was exactly like 

 Lepidodendron. 



The Sigillariaceae are much like the Lepidodendrons in essential 

 features, but differed considerably in habit. They attained their 

 maximum development in the Upper Carboniferous and gradually 

 waned during the Permian, although they appear to have survived 

 into the Lower Triassic. The trunks were generally massive and for 

 the most part unbranched, giving them a peculiar appearance and at 

 one time suggesting a relationship with the cycadophytes, since dis- 

 credited. 



Some specimens 6 feet in diameter at the base had tapered to 1 foot 

 in diameter 18 feet above the base, while a French specimen was found 

 preserved for a length of 71 feet, which was 2 feet in diameter at one 

 end and 1 foot 8 inches at the other. The leaves were persistent 

 toward the top of the stem and in some cases were very long and grass- 

 like. Stem impressions, which, like those of Lepidodendron, are 

 exceedingly common throughout the coal measures, can readily be dis- 

 tinguished by their vertically arranged scars often on prominent ribs, 

 by the slight development of bolsters, and by the scars being wider 

 than high, with the angles at the sides and rounded above and below. 

 Very many species have been described and the variations observed 

 are very useful for stratigraphic purposes, and have resulted in an 

 elaborate analysis of the types of surface ornamentation. These fall 

 naturally into two main groups: The EuSigillariae with ribbed steins, 

 and the SubSigillariae with smooth stems. 



The Eusigillariae show broad longitudinal ribs separated by fur- 

 rows and are segregated into two subordinate groups: i. e., Favu- 

 laria, in which the ribs are separated by zigzag furrows and the scars 

 by transverse furrows; and Rhytidolepsis, in which the ribs are sepa- 

 rated by straight furrows and are often much broader than the close 

 set or spaced scars. Where the furrows are broad and intercalated, 



