154 
DR. HOOKER AND MR. BINNEY ON TRIGONOCARPONS 
inner, which gradually become longer, are filled with a viscid resinous fluid. To- 
wards the inner surface of this integument the cells are much elongated, and become 
mixed with scalariform and annulate and subspiral vessels and long empty cells (fig. 8 a 
and fig. 9); within this is a thin crustaceous integument, formed of densely packed, 
vertically elongated sclerogen cells (figs. 10, 11), and this again is lined by a delicate 
coat of annulated cells similar to those outside it (fig. 15): all these integuments 
are perforated in a young state for the impregnation of the ovule, and this is the 
only explanation or analogue which we can offer of the canal leading down to the 
cavity of the Trigonocmyon. An extremely delicate membrane (fig. 16) surrounds 
the albumen of Salishuria, and the latter is formed of a densely packed mass of cells 
(fig. 17) enclosing minute starch granules* (fig. 18). 
The absence of any crustaceous integument exactly similar to Salishuria is to be 
remarked in Trigonocarpon ; but these organs are so extensively modified in the allies 
of Salishuria, that the suppression of one in Trigonocarpon, or its representation by the 
middle coat (which certainly appears to have been much indurated), is a consideration 
of comparatively little moment, whilst the resemblance between the structures which 
we have described in the two genera is very remarkable. 
The supposed alliance of Trigonocarpon with Coniferoe does not, however, rest on 
the above comparison alone, but to a certain extent upon collateral evidence: thus, 
the presence of wood, closely resembling what is supposed to be typical of Coniferoe, 
is abundant in the carboniferous formation ; while the absence of cones and of foliage 
similar to that of those Coniferoe of the present day, whose seeds are similarly 
arranged, renders it probable that the drupe-bearing division of the Order, which is 
now chiefly prevalent in the Southern hemisphere, predominated in the carboniferous 
aera. The remarkable fact too, of the resemblance of Noggerathia leaves (a carboni- 
ferous genus) to that of Salishuria, was long ago indicated by Lindley and Hutton ; 
and though adduced by Brongniart in favour of Trigonocarpon (which is some- 
times found associated with these leaves) being allied to Cycadeoe, accords better 
with the assumption of both being coniferous. ^ 
The association of Trigonocarpon, in the nodules we have examined, unfortunately 
offers no clue to their affinities, as we find neither cycadeous nor coniferous wood 
along with them ; while of plants belonging to or allied to Filices and Lycopodiacese 
we find abundant remains in close proximity with the Trigonocarpons, but in the 
latter there are no traces of the tissues so prevalent in these plants. It is further to 
be remarked, in connection with these plants, that Salishuria fruit not only presents 
no trace of coniferous tissues, but abounds in scalariform annular and subspiral 
vessels, which are supposed to be very rare in the order to which it belongs. 
* These analyses are added in the hope that they may aid others in the investigation of this interesting sub- 
ject, should any one be so fortunate as to detect any contents within the cavity of Trigonocarpon. We have also 
at fig. 12 figured some loose sclerogen cells that are found occasionally on the inner wall of the crustaceous 
integument, and at figs. 13 and 14 some modifications of the cellular tissue in the inner coat. 
