Igtt] COULTER & LAND—LEPIDOSTROBUS 451 
The cells of the ligule itself are small and almost isodiametric; and 
its tip is invariably withered. 
The most characteristic feature of Lepidostrobus is the radially 
elongated sporangium, which extends along the whole adaxial face 
of the stalk of the sporophyll. In our specimen the sporangium is 
17 mm. long and 2.5—3 mm. broad, attached along the central axis 
of the stalk by a narrow connection, and bulging pouchlike beyond 
the sides of the stalk, until the latter broadens into winglike exten- 
sions near the lamina. Only in the distal region of the sporangium 
is there any evidence of a ‘‘subarchesporial pad,” which appears 
in section as a broad and low dome of tissue (fig. 12); there is no 
evidence of any radiating sterile tracts within the sporangium. 
The most notable feature of the sporangium, aside from its 
radial extension, is its dehiscence (fig. 6). A series of transverse 
sections indicates this very clearly (figs. 9-13), and also served 
as the basis of a restoration. The sporangium dehisces_ longi- 
tudinally along the median line for a little more than half its length 
from the base, and then the line of dehiscence forks and is repre- 
sented in the distal half of the sporangium by two diverging lines, 
which leaves between them a large triangular flap of the sporangium 
wall. In most cases the structure of the outermost layer of spo- 
rangium wall is well preserved, consisting of the characteristic 
“prismatic palisade-like cells” (figs. 17 and 18). The wall, under 
pressure of the adjacent structures, is quite definitely angled 
(figs. 9 and 16), and at these angles the palisade-like cells are con- 
- Spicuously elongated, and within the angles there are usually traces 
of the more delicate inner wall layers. No special mechanism of 
dehiscence was discovered, although it is reasonable to suppose 
that one exists in the case of this singular dichotomous or tri- 
radial dehiscence. Since the distal ends of the sporangia abut 
against the heavy interlocking bases of the laminae, it is altogether 
Probable that the continuation of the median longitudinal dehis- 
cence becomes mechanically impossible. 
It is to be regretted that the basal part of the strobilus was not 
secured, so that the question of heterospory might have been 
answered. The spores observed are probably microspores, and 
their appearance is sufficiently indicated in fig. 19. 
