62 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



The vascular axis is surrounded by a cortex composed of three 

 zones. The inner and middle zones are formed of delicate cells 

 and the outer of dense thick-walled cells. 



Each pedicel supports a single oblong sporangium attached to 

 it by a longitudinal band of parenchyma. 



From the distal end of the pedicel the limb of the sporophyll 

 rises abruptly upwards and is frequently "heeled," giving a 

 slightly peltate termination to the pedicel. In the angle formed 

 by the outer (end) wall of the sporangium and the upright blade 

 of the sporophyll is a small ligule. 



The sporangium wall consists of a single layer of palisadal cells, 

 the structure of the macrosporangia and microsporanyia being 

 similar.' 



Remarks. — The structure of the bracts or sporophylls is illus- 

 trated in fig. 8, which shows Lepidostrobus anthemis, Konig sp., 

 in transverse section. The limb of the 

 bract is shown at a and the basal portion 

 ,. a or pedicel at h. At c is marked the 

 position of the axis. In the uncom- 

 pressed condition the limb a would rise 



^ 



N 



c up at almost right angles to the spor- 

 angia! portion b. 



In Lepidostrobus Jimbriatus, Kidston," 



Fig. 8. — Lepidostrobus the limb is strongly ciliated, but, as only 



anthemis, Konig sp. the bracts of this species are known, it is 



Transverse section of uncertain whether it belongs to Lepi- 



cone — a, limb of bract ; j i j £ ii, n- j 



' , , . ,' dodendron or one oi the allied genera. 

 h, portion to which r ■ 7 7 • i 



sporangium is attached; ^^ ^J^ ''^^es where Lepidostrobi can be 

 e, axis. Natural size definitely ascribed to Lepidodendron, as 

 (No. 1032). far as we know the bracts are free fi'om 



such ciliate appendages. 

 The form of the bract varies according to the species, being 

 generally more or less lanceolate. They vary also in size from 

 less than an inch to over four inches in length in Lepidostrobus 



^ There is no development of secondary xylem, and its absence is 

 characteristic of the vascular system of fugaceous organs. 



* From the Cement-stone Group of the Calciferous Sandstone Series, Lewis- 

 burn, North Tyne, Northumberland, Trans. Roy. Soc. Edin., Vol. XXX., 

 p. 543, PI. XXXI., figs. 2-4. 



