THE CARBONIFEROUS AND PERMIAN FLORAS. 459 



Lycopodiaceous trees which have " thick branches, trans- 

 versely-elongated leaf-scars, each with three vascular points, 

 and placed on elevated or scale-like protuberances, long one- 

 nerved leaves, and large lateral strobiles in vertical rows or 

 spirally disposed" (Dawson). 



e. Sigillarioids. — The three chief genera included under 

 this head are Sigillaria, Bliytidolepis, and Favularia, of which 

 the first is the most important. The Sigillarioids commence 

 their existence, so far as known, in the Devonian period, but 

 they attain their maximum in the Carboniferous ; and — un- 

 like the Lepidodendroids — they are not known to occur in 

 the Permian period. They are comparatively gigantic in 

 size, often attaining a height of from. thirty to fifty feet or 

 more ; but though abundant and well preserved, great diver- 

 gence of opinion prevails as to their true affinities. The name 

 of Sigillarioids (Lat. sigilla, little seals or images) is derived 

 from the fact that the bark is marked with seal-like impres- 

 sions or leaf-scars (fig. 709). 



According to Dawson, Sigillaria proper is distinguished by 

 its strong ribs, " which are usually much broader than the 



Fig. T09. — Fragment of Sigillaria Grceseri. The left-hand figure shows a small 

 portion enlarged. Carboniferous. 



oval or elliptical tripunctate areoles, and are striated longi- 

 tudinally." The stem consists of a central pith, which is 

 transversely partitioned, as in the so-called Sternbergim. The 



