10 DESCRIPTIVE CATALOGUE 



known English species in Corda's more recently founded species, 

 Tempskya Scliimperi, which had been established in 1845 by 

 Corda without any reference to the English forms. This fact 

 appears to be the cause of the inclusion of all the English fossils 

 in T. Schimperi by succeeding writers, though the condition of 

 preservation both in Corda's type and in the numerous English 

 representatives is so incomplete as to make it really impossible 

 to be certain of their identity. 



Indeed, until the recent description of the much better 

 preserved T. llossica (Kidston & Gwynne-Vaughan, 1912), the 

 most fundamental facts about the genus were unknown. Solms- 

 Laubach (1891 A, p. 159) referred to the " Tempskya condition " 

 us though it were a special mode of preservation rather than a 

 true genus, and even so recently as 1894 Seward (p. 149) 

 wrote : " It will be well for the present to retain Corda's 

 term, if we regard it as implying a particular manner of pre- 

 servation rather than any well-defined generic characters." 

 This was due to the poor nature of the tissue-petrifactions of 

 the specimens, though imperfect examples were widespread, 

 abundant, and easy of identification. 



1'rof. Soward gives so full an account of the earlier literature 

 of the genus (Seward, 1894, pp. 148-158) that there is no need 

 to recapitulate it. 



Of the older writers Schenk (1871 B, p. 200) most nearly 

 approached the truth as it is now known, for he repudiated the 

 view that the plant was merely the peripheral part of an 

 ordinary tree-fern, and looked on it as a distinct genus in which 

 there were several steles of various types imbedded in paren- 

 chyma. It is now clear that the separate steles were not parts 

 of a polystelic axis, but each was the solenostelic axis of an 

 independent stem. These separate small stems were aggregated 

 to form a " false stem " of considerable size, and were surrounded 

 by a common plexus of their adventitious roots. In its manner 

 of growth the genus is unparalleled by any known foseil, and 

 only approached among living plants by the carious //<->;? iY<7w 

 crenulata recently described by Dr. Schoute from Java (see 

 Schoute, 1906). 



The small axes which Kidston & Gwynne-Vaughan showed to 

 be distinct stems, i. e. primary axes, were those generally 

 desoribed (if mentioned at all) by previous writers as "petioles." 



