PALEOZOIC CONE-GENUS LEPIDOSTEOBUS. 207 



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described. The sporopliyll has a thin, leafy lamina, quite different from the cushion- 

 like body which terminates the sporophyll lobe of L. Brownli. The distal end of the 

 sporangium is peculiar in archinj^ over and concealing the ligule. The latter organ, 

 which was first discovered by Maslen* in this species, now appears to be present 

 universally in connexion with the sporophylls of Lepidostrohus. Maslen f distinguishes 

 within the species L. oldhcmiius three forms, which he calls (a), (/3), and (y). The 

 chief diff*erences between these types lie in the anatomical structure of the axis. 

 Maslen's form (/3) represents the species as originally described by Williamson. 



Coulter and Land % have described a petrified cone from the Coal Measures of Iowa 

 which appears to belong to the type of L. oldhamius. 



The structure of a large cone from the Upper Carboniferous (Westphalian) of the 

 Donetz basin has recently been discussed in great detail by Zalessky §, who has named 

 it Lepidostrohus Bertruudi. This fructification does not differ in any essential ana- 

 tomical feature from X. oldhamius , but, at the same time, there is no doubt that it 



represents a distinct species. 



Ilomosporous or microsporous cones of the type of L. oldhamius are not, however, the 

 only forms of Lepidostrobus met with in the Upper Carboniferous rocks. Williamson || 



ves a ficure of a section of a slender cone from the Coal Measures which ditt'ers 



g 



b 



markedly from both i. ohUuwiius and L. Bertrandi. la Williamson's text this 

 section is dismissed with a biief mention, and we had no detailed information about 

 it until it was redescribed by Mashm «|[ under the name of L.foliaceus. The form 

 of the sporophyll and the histology of the lamina are peculiar, and make it easy 

 to recognise the species at a glance. Williamson's section contained only microspores, 

 but our knowledge of the cone has now been rendered much more complete by 

 Mrs. Scott's** discovery that certain megaspores with peculiar appendages, with which 

 she had been acquainted for some time as isolated objects, were borne in sporangia which 

 belonged to L.foliaceus. Tliis species thus ranks as a heterosporous Lepidostrohus. 



Little is known with certainty on the subject of the attribution of these various cones 

 to the species of Lepidodendron which bore them. Williamson ft pointed out that it 

 was extremely probable that the heterosporous cone, which he described from Burnt- 

 island, was the fructification of Lepidodendron Veltheimiamim, and Scott JJ has contiraied 

 this attribution and employed the name Lepidostrohus Veltheimianus for the cones. In 

 Lepidostrohus Wimschianus, another heterosporous cone from the same horizon found 

 in Arran, we appear to liave a second instance in which the structure both of the stem 

 and the strobilus are known §§. These two species seem, however, to be the only 

 instances in which we are definitely acquainted with the internal structure both 

 of the fructification and of the tree which bore it. 



In certain cases it is possible to ideiitify cones whose internal structure is preserved 



Maslen, A. J. ('98). t ilaslen, A. J. ('99). t Coulter, J. M., & Land, W. J. O. ('11). 



« Zalessky M ('08). li ^Villiamsoa, W. C. ('94), p. 27, aud pi. 9. fig. 57. 



t Main, A. J. ('99), p. 373, and pi. 38. %s. 36-39. ** Scott, R. ^OG). 



tt WilHarason, W. C. ('73), p. 94. 



§§ Knnej, E. W. ('71), p. 56, pi. 11, and Williamson ('94), p. 29. 



tt Scott, D. II. ('00), p. 171. 



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