4 6 
M. G. Sykes. 
position of the sporangium is nearly the same in both species, it is 
not quite in the axil in L. carolinianum, but is slightly pushed out 
oh to the sporophyll axis (Text-fig. 6, VIII.); the cells of the very 
short sporangium-pedicel in L. carolinianum have their cell-walls 
lignified in patches like the similar cells in L. inundatum. 
Text-fig. 5. 
Text figs. 5 and 6 represent diagrammatic longitudinal sections of 
sporophylls of L. inundation and L. carolinianum. (w=mucilage cavity, 
6 =lignified cells in sporangium pedicel, r=cuticularised epidermis). Each 
sporophyll has a dorsal flap, and bears a shortly-stalked sporangium, which is 
axillary in L. inundation, but not quite axillary in L. carolinianum. 
The dehiscence of the sporangium in both these species is of 
some interest. It takes place in L. inundatum by means of a slit 
along a line of cells on the ventral surface of the sporangium, on 
the side furthest from the axis of the cone.' In L. carolinianum 
the slit is on the dorsal side, hut is slightly displaced laterally, 
The two flaps of the dehisced sporangium are thus of unequal size, 
and the spores are liberated in the most convenient position for 
dissemination, that is, nearest the opening between the sporophylls. 
This adaptation is still more strikingly illustrated in some of the 
more complicated cones. 
The systematic position of L. volubile is a matter of some 
difficulty. It is placed by Baker in his sub-genus 4, which includes 
the other heterophyllous forms, L. complanatum, L. carolinianum, 
etc. Pritzel has split up this sub-genus, believing that the common 
possession of heterophylly is not a valuable systematic character, 
and while he places L. carolinianum with L. inundatum, and L. 
1 Goebel, Organography II., pp. 582, 583, Fig. 378, 
