220 



DE. AGNES AEBER ON THE 



have dehisced. The nuinher of sporophyll traces cut across in a single transverse section 

 of the axis does not appear to exceed 20, whereas in the forms of Lej>ldostrohus oldhamius 

 descrihed by Maslen * the number ranges from 30 to 60. This difference is no doubt 

 correlated with the small dimensions of the axis in 1>. gracilis. The ligule, or at least 

 its base, is sunk in a definite ligular pit (PL 26. fig. 41), while, according to Maslen f, 

 " the complete absence of a ligular chamber " characterises Z. oldhamius. The structure 

 of the sporophyll pedicel also differs from that of i. oldhamius, and more closely recalls 

 that of X. foliacens % and L. Binneyanus § in possessing two lateral, sclerised cushions, 

 between which the sporangium is attached by means of a ridge of sterile tissue. In the 

 details of its histology, however, the pedicel differs markedly from that of L. Binneyanus 

 (see p. 213), while the lamina differs no less widely from that of L. foliacens with its 

 large-celled parenchyma and secretory cells. 



(10) Diagnosis. 



LEriDOSTUOBUS GRACILIS, sp. nov. 



Morizon. Lower Coal Measures. 



Cone very slender in proportion to its length ; about 1 cm. in diameter. 



Vascular cylinder of cone axis about 0'3 mm. in diameter, enclosing a pith. 



Outer zone of inner cortex^ a resistant, dark-coloured tissue. 



Sp07^ophyll ;pedicel about 4 mm. in length. Short dorsal keel and a ventral sclerised 



cushion on either side of the median line. 



Sporophyll lamina not less than 12 mm. in length. Tissue dark and resistant towards 



the dorsal surface. 



Ligule sunk in a ligular pit, at least as regards its base. 



Sporangium attached to the pedicel by a slender median ridge of tissue, which is 

 carried up into the cavity of the sporangium as a sterile plate. 



Spores^ diameter about 0*028 mm., slightly bordered in the equatorial plane. 



(iii.) Lepidostrobus oldhamius. Will., f. minor. 



(PI. 23. figs. 13 & 14 ; PL 26. figs. 43-49.) 



L 



(1) Material. 



One of the Lower Coal Measure blocks in the Binney Collection, Sedgwick Museum 

 contained a cone which, although it bears a general resemblance to Lepidostrobus old 



hamius. Will., yet diverges from it sufficiently to entitle it to rank at least as a " form 

 of this species. The cone has been cut up into five longitudinal sections |1, of which 

 PL 23. fig. 13 represents a typical example. 



Maslen, A. J. ('99). f Maslen, A. J. ('98), p. 259. 



+ Maslen, A. J. ('99), p. 374, and pi. 38. figs. 37 & 38. 

 § See Pi. 22. fig. 7 and PI. 25. figs. 26 & 27 of the present paper 



Binney Coll , Sedgwick Museum, AM. (25-29). 



