XXIX] PTERISPERMOSTROBUS 67 



4x3 mm., characterised by 3 5 apical lobes extending 2 mm. 

 beyond the distal end of the seed-like organ and resembling a 

 cupule. In this as in many other cases it is impossible to determine 

 the true nature of the reproductive bodies, whether they are 

 small seeds or groups of microsporangia : the new generic name 

 serves a useful purpose though it is not always possible definitely 

 to refer doubtful fructifications of this kind to a Pteridosperm. 

 The organs in question may also be compared with Codonotheca?-. 



Pterispermostrobus pusillus (Nathorst). 



The name, Codonotheca pusilla, is given by Nathorst 2 to some 

 doubtful specimens from the Culm of Spitzbergen representing 

 short stalks bearing linear-lanceolate scale-like bodies, 9 10 mm. 

 long by 1 mm. broad, coalescent at the base. Nathorst compares 

 them with Sellard's species, Codonotheca caduca, but adds that they 

 may be cupules of some Pteridosperm and calls attention to 

 their resemblance to some fossils figured by Carpentier as 

 Calyinmatotheca acuta. Both Nathorst's species and the French 

 specimens described by Carpentier 3 as cupules may be referred 

 to Dr Stopes' genus Pterispermostrobus as their morphological 

 nature cannot be determined. 



v. Roots. 



In 1876 Williamson 4 described some petrified vegetative 

 organs from the Lower Coal Measures of Lancashire under the 

 name Kaloxylon Hooker % characterised by a division of the 

 secondary xylem into cuneate masses (fig. 415, C) like those in 

 some recent Bignoniaceous stems. Williamson at first believed 

 Kaloxylon to be a stem, but in a later memoir he expressed the 

 opinion that 'it is difficult to believe that these organs have been 

 other than roots' 5 . Felix 6 had meanwhile described a specimen 

 from the Coal Measures of Westphalia as Kaloxylon cf. Hookeri 

 and suggested that it might be a waterplant. In 1894 Williamson 

 and Scott 7 demonstrated that Kaloxylon Hookeri is the root of 

 Lyginopteris, a conclusion independently reached by Hick 8 . 



1 See page 124. 2 Nathorst (14) p. 23, PI. xv. fig. 43. 



3 Carpentier (13) p. 391. 4 Williamson (76) B. 5 Williamson (87) p. 297, 



6 Felix (86) A. p. 51. 7 Williamson and Scott (94). 8 Hick (95) p. 114. 



52 



