I 



PALEOZOIC CONE-GENUS LEPIDOSTEOBUS. 211 



L. oldJiamius. The same feature is also oLservable in certain sections of the species 

 in the Manchester University Collection *. 



The structure which we have been considering is not confined to JO. oldhamius and 

 L,foUaceus, but is found, in addition, in the new forms of Lepidostrohus which will 

 be described later in the present paper. It has also been previously recorded in 

 L. Veltheimiamis f and in an unnamed species % from the Coal Measures ; while sterile 

 upgrowths, taking the form of pegs rather than plates, are known in L. Broionii §. 

 I am hence inclined to think that the occurrence of some form of sterile upgrowth 

 from the sporangial floor may eventually prove to be characteristic of all forms of 

 Lepidostrohus \\ which are microsporous or homosporous ; such a structure does not seem 

 at present to have been recognised in any megasporangium. The fact that these sterile 

 plates have been hitherto overlooked in so well-known a type as X. oldhamius is no doubt 

 due to the circumstance that the delicate tissue of which they are composed is liable to 

 shrivel beyond recognition as the sporangia ripen. 



The Occurrence of Periderm in the Sporophylls of Lepidostrobus 



Will 



In Williamson's orisjinal 



transverse section of Lepidostrobus oldhamius ^ there are 

 distinct indications of a radial arrangement of the cells of the sporophyll lamina towards 

 the dorsal surface. This" grouping is sufficiently regular to suggest that periderm is in 

 process of formation. The same appearance of cork at the dorsal surface of the sporo- 

 phyll lobe occurs in various sections of cones belonging to L, oldhamius in Dr. Scott's 

 Collection, e. g. S. 1200, a part of a sporophyll from which is shown in transverse section 



in PI 27. fig. 56. 



It seems probable that such cork formation was widely prevalent in the sporophylls of 



Lepidostrohus, since it also occurs in three of the forms described in the present paper— 

 L. Binneyanus, sp. nov., L. gracilis, sp. nov., and L. oldhamius i pilosus (cf PL 24. 

 fig. 20, PI. 25. figs. 29 & 36, and Text-fig. 3, B & C). As will be shown on p. 227, the 

 periderm in L. oldhamius f. pilosus appears to have been hypodermal in origin, and it is 

 not improbable that this was also true in the case of other species. PL 25. fig. 36 



presents a ti 



through the dorsal surface of a sporojdiyll of L 



Here the cork has quite the appearance of being hypodermal. In L. Bimieyanus also, 

 where the periderm seems at first glance to be epidermal (PI. 25. fig. 29), it is possible 

 that the true epidermis may have been discarded. 



* ilanchester Tnlversity Coll., Q.452; Q. 456 ; Q. 457. 



t Williamson, \V. C. ('73), p. 295 & pi. 44. figs. 23, 24, 25. 



t Bower, F. 0. ('94), p. 529 & pi. 48. figs. 101 & 102. 



§ Brown, R. ('51), p. 471 ; Bower, F. 0. ('94), p. 527 & pi. 48. figs. 96-100^; Z( 



II A similar conclusion seems to have been reached by Bower, F. 0. ('08), p. 325. 



% 



