Seed-like fructification in certain Palceozoic Lycopods. 307 



measures, some from Hough Hill, Stalybridge, others from Moorside, 

 Oldham. Numerous sections were cut by Mr. Lomax and Mr. Wild. 

 A closely similar fructification occurs, at a much lower horizon, in the 

 Burntisland beds of the Calciferous Sandstone Series. 



The strobilus is of the ordinary Lepidostrobus type. The cylindrical 

 axis bears numerous spirally disposed sporophylls, each of which con- 

 sists of a long horizontal pedicel, expanding at the distal end into a 

 rather thick lamina, which turns vertically upwards. 



Anatomically, the structure is also that of a Lepidostrobus. The 

 stele which traverses the axis has a narrow ring of centripetal wood, 

 and a large pith ; the leaf-trace bundles which pass out to the sporo- 

 phylls are collateral in structure, and agree closely with those described 

 by Mr. Maslen in Lepidostrobus Oldhamius* 



The ligule is sometimes well preserved ; it is seated in a depression 

 of the upper surface of the sporophyll, at the distal end of the spo- 

 rangium, and is thus in the normal position.! 



With one exception, the specimens of the strobilus are immature, and 

 their tissues not quite fully differentiated. These younger specimens 

 bear sporangia which are essentially those of a Lepidostrobus. A 

 single large sporangium is seated on the upper surface of the hori- 

 zontal pedicel of each sporophyll, to the median line of which it is 

 attached along almost its whole length. 



The sporangium narrows out towards the top, and terminates above 

 in a well-marked ridge; in general form it resembles Williamson's 

 ' Cardiocarpon an&nuilum, but in the immature condition there is no 

 integument. The outer layer of the sporangial wall has the columnar 

 or palisade-like structure characteristic of Lepidostrobus ; it is lined by 

 a more delicate inner layer, which may be several cells thick. 



So far the structure is simply that of a Lepidostrobus with rather 

 thick-walled sporangia. 



Within the sporangial cavity, the membranes of the megaspores are 

 usually preserved ; a single large megaspore almost fills the spo- 

 rangium, but smaller, abortive spores, with thicker walls, are also 

 present. Some specimens show that three of these abortive spores 

 were present in each sporangium. It appears, then, that a single tetrad 

 was developed in each megasporangium, and that of the four sister- 

 cells one only came to perfection, constituting the functional megaspore. 



In one specimen, discovered by Mr. Wild, the strobilus is in a more 

 advanced condition. In its upper part the sporophylls simply bear 

 sporangia, as above described, but lower down in the cone these are 

 replaced by integumented, seed-like structures, identical with the 

 detached bodies called Gardiocarpon aiwnudum by Williamson. 



* Maslen, " The Structure of Lepidostrobus," ' Trans. Linn. Soc.,' London, 

 SOT. 2, vol. 5, 1899. 



t Maslen, " The Ligule in Lepidostrobus," ' Annals of Botany,' vol. 12, 1898. 



