198 PLANTS OF THE COAL. 



to the splendid work of M. Brongniart, from which the 

 preceding figures are taken (fig. 133). 



SieuLLABi^). The same deposits of the coal aiford nume- 

 rous fluted stems, or trunks of trees, which, when they occur 

 in the shale, are usually flattened by the pressure of the 

 superincumbent strata, but when placed vertically or obliquely 

 in the grit, or sandstone, are round and uncompressed. From 

 presenting small impressions, occasioned by the decay and 

 fall of the leaf-stalks, resembling markings made by a seal, 

 they have obtained the name of sigillaricB. They have also 

 been figured and described by various writers on Fossil 

 Botany, under the names ofrfytidohpis, alveolaria, favularia, 

 catenaria, &c. They have hitherto been considered as 

 monocotyledonous plants ; but later observers, particularly 

 the late Mr. Bowman, in a communication to the Geological 

 Society, on the fossil trees, discovered on the Bolton Kail- 

 way,* endeavours to show that the sigillarice belonged to the 

 dicotyledonous division. He founds this conclusion on the 

 following evidence : 



The irregular, longitudinal and discontinuous, or anasto- 

 mosing furrows on the surface of the stems ; the swelling out 

 of the stems at their base ; their angle of dip, or downward 

 direction of the roots ; characters which, he observes, are con- 

 stantly observable in dicotyledonous, but never in monocoty- 

 ledonous plants. He adduces marks of striae as proving that 

 these trees have a separable bark, and finally, in slices of a 

 tree of this kind, prepared for microscopic investigation, he 

 discovered traces of medullary rays, which are universally 

 recognised as indisputable proofs of dicotyledonous structure. 

 The supposition that these plants were hollow, a circumstance 

 which would be fatal to their dicotyledonous character, had 

 previously been denied by Mr. Hawkshaw, who had stated 

 that in tropical climates the interior of solid hard- wood trees 

 is often consumed by insects, in an extremely short space, 

 leaving the bark intact, and the tree apparently sound. 

 Hence it is inferred, that in the ultra-tropical climates of 

 the carboniferous epoch, solid trees might have been inter- 

 nally destroyed, and rendered hollow in a short period of time. 



While the sigillarice are thus generally regarded as dico- 

 tyledonous, or exogenous trees, Dr. Lindley has divided from 



* See Proceedings, vol. 3, No. 63, p. 273. 



