DEVONIAN AGE. 



269 



sentatives of the order (pp. 242, 245), and which in the Hamilton 

 are the least common kind ; (2) the Lepidodendrids, having the scars 

 which mark the places of the leaves in alternate or quincunx order 

 (Fig. 525) ; and (3) the Sigillarids, which have the scars in vertical 

 series (Fig. 526). 



The Lepidodendrids were in part trees, and they much resembled 

 in habit modern Spruces and Pines, the leaves having been long and 

 narrow and crowded over the branches. A portion of the scarred 

 exterior of a branch, from New York, is represented in Fig. 525. 

 Good examples of such scars are to be found on a small branch of 

 a common spruce. Fig. 527 represents a broad leaf of the genus 

 Cordaites, which belonged to a Lycopod, according to some authori- 

 ties, but more probably to a Conifer (p. 329). 



Figs. 525-530. 



Acrogens. — Fig. 525, Lepidodendron primsevum ; 526 Sigillaria Hallii ; 527, Cordaites Robbii; 

 528, Neuropteris polymorphs ; 529, 5S0, Cyclopteris Jacksoni. 



The Sigillarids grew up as stout trunks, some of them thirty or more 

 feet high, with rarely a branch, and with long linear leaves (or fronds) 

 about the summit. Fig. 526 represents a portion of a very small 

 species, from New York, showing the vertical series of scars. Trunks 

 of Sigillaria have been found having a base of spreading branches 

 looking like roots ; but the supposed roots, according to Lesquereux, 

 are underwater stems. These stems have round, scattered, pit-like 

 depressions over the surface, where the underwater leaves were at- 

 tached, and are called Stigmarice, from the Latin stigma, a dot. Part 

 of a stem of a Carboniferous Stigmaria is represented in Fig. 624, 



