AS COMPARED WITH THAT OF THE PRESENT DAY. 



419 



these have been called " Endogenites" are scarcely two inches in 

 diameter, and are generally obliquely placed in the substance of 

 specimens five feet and upwards in girth. That this slender column 

 represented all the vascular tissue of this plant, I cannot doubt, from 

 examination of Stigmarice, whose vascular column often assumes the 

 same appearance. 



Affinities. — These have been very much discussed by various natu- 

 ralists, who have eagerly seized upon the few botanical characters the 

 very imperfect fossils present. 



In noticing its outward appearance, little allusion was made to the 

 S. lepidodendrifolia, the only species of the genus whose foliage has 

 been described, and which, if really a congener of S. Organum, &c, 

 would, doubtless, ally all these plants closely to Lepidodendron itself. 

 But I am inclined to pronounce M. Brongniart's figure of this plant* to 

 be a true Lepidodendron, though possessed of scars more resembling 

 those of many Sigillarice, for it wants the fluted stem. The leaves of 

 this S. lepidodendrifolia seem to be what was considered a species of 

 grass or sedge, and placed in the genus Cyperites. 



Did the great Sigillarice bear leaves like those of Lepidodendron, 

 they could hardly escape petrifaction in the shales, especially where 

 the Cyperites so abound ; but there is nothing whatever in the shales 

 which we can recognise as having been in any probability an organ of 

 or appendage to Sigillarice. 



One point which must not be overlooked, 

 namely, the possibility of the scars upon young 

 Sigillaria? being quincuncially or spirally 

 arranged, as in Lepidodendron, and after- 

 wards owing to the dilatation of the trunk 

 being disposed in lines. The reverse of this 

 is sufficiently obvious in some recent Coniferce, 

 as the Pinus Webbiana, where the young leaf- 

 scars are disposed in parallel lines, which be- 

 come disturbed through age, and appear ulti- 

 mately arranged in the old branches, as shown 

 in the accompanying wood-cut (Fig. 11). 



That there are Lepidodendrons generically 

 distinct from Sigillarice cannot be doubted ; 

 for specimens of the former genus, many feet 

 long, are known, having their scars spirally 

 arranged throughout ; but this is not incon- 

 sistent with the hypothesis that other plants 

 in a certain state, apparently belonging to the 



* Sigillaria lepidodendrifolia, " Brong. Hist. Veg. Foss.," vol. ii. t. 161. 

 II. 2 G 



Fig. 11. 



