ii8 



VASCULAR CRYPTOGAMS 



Sigillariostrobm, the fructification of Sigillaria, is extremely rare. It 

 was a cone resembling Lepidostrobus, with the sporanges placed singly 

 on the base of the sporophylls. The sporophylls are broadly lanceolate 

 and apiculate. Only one kind of spore has at present been discovered, 

 the megaspores, but it may be regarded as certain that these were asso- 

 ciated with a second and smaller kind. 



The fossils known as Stigmaria are the roots of Sigillaria, the two 

 having been not unfrequently found in connection with one another. 

 They occur in the Devonian and Carboniferous formations. Fragments 

 have been found from twenty to thirty feet or more in length (S. ficoides, 

 Brongn.), cylindrical arid unbranched, or the branching always dichoto- 

 mous, the two branches running in a nearly parallel direction. The 

 surface is smooth, with numerous shallow saucer-like depressions, the 

 scars of the rootlets, some of which are still very commonly found 

 attached to the primary root. The Stigmarije obviously lengthened 



Fig. (yi.— Stigmaria jicoides Erongn. with rootlets. (After Solms-Laubach.) 



exclusively by apical growth. Transverse section shows a hollow 

 ' vascular ' cylinder, broken by meshes for the passage of the bundles 

 of the rootlets, and consisting of scalariform tracheides with a central 

 parenchyipatous tissue or ' medulla.' In the rootlets the single central 

 bundle consists of a few scalariform tracheides, which leave the cylinder 

 as a triangular bundle, but become circular in the rootlets. 



Under the term Lycopodites are included a number of fossil forms, 

 the fructification of which is either entirely unknown, or is not in a suf- 

 ficiently well-preserved state for definite determination. Some of the 

 leafy stems ought possibly to be referred to Coniferse ; others, with 

 leaves of one kind only, perhaps belong to Lycopodiaceae ; while others, 

 with leaves of two different kinds, are Selaginellacese. From beds near 

 the bottom of the Carboniferous series there is a species with thick 

 club-shaped terminal fructification, bearing a striking resemblance to 

 I.ycopodium Phlegmaria (Lycopodites Stockii, Kidst.). Ptilophyton 



