216 
PKOGRESS OF MICROSCOPICAL SCIENCE. 
regarded by M. Brongniart as pollen-grains — an opinion in wliich 
the author concurs. External to the lagenostome the second or outer 
division of the nucular membrane forms a remarkable " canopy," 
which hangs down from the micropyle, enclosing the lagenostome 
within ten sharply defined and regular crescentic folds, the con- 
cavities of which are directed outwards. The walls of this lageno- 
stome and of the " canopy " correspond with the nucular membrane 
in consisting of flattened prosenchymatous cells. The perispermic 
membrane, on the other hand, looks structureless, save that it appears 
to have had imbedded in it an innumerable multitude of minute 
crystals, like those observed by Dr. Hooker on the spicular cells of 
Welwitsdiia. A second species the author designates Lagenostoma 
physoides. In this the apex of the endospermic sac contracts into a 
mammilliform prolongation, overlapped by the base of the lageno- 
stome, which overhangs it as a bladder half full of water might be 
made to overhang the neck of a soda-water bottle upon which it 
rested. This species has other distinctive structural peculiarities. 
For a second genus of new seeds the author proposes the name of 
Conostoma. G. ohlonga, from Oldham, is about '18 of an inch in length. 
Here, again, we have an endosperm enclosed in a perispermic mem- 
brane, and this in turn is encased within a nucular one, the whole 
being invested by a dense testa. The lagenostome is again formed 
out of divisions of the apical part of the nucular membrane ; but it 
assumes a funnel-shape at its base, whilst its upper extremity is 
continuous with the micropyle. A second species, named C. ovalis, is 
from the Burntisland deposit, and is more ovate than C. ohlonga. In 
it the lagenostome assumes a remarkably funnel-shaped contour. The 
same deposit has furnished a third species, C. intermedia. To another 
remarkable seed from Oldham the author gives the name of Malaco- 
testa ohlonga, of which the maximum length, exclusive of its funiculus, 
has been about • 25. Its exotesta has been soft and parenchymatous, 
with a prosenchymatous inner (nucular ?) membrane. The micropyle 
has been remarkably wide with incurved margins at the exostome, 
and enclosing a mass of delicate parenchyma through which a canal 
passed. The author has obtained a fine series both of longitudinal 
and transverse sections of Trigonocarjpum olivceforme, the seed long 
ago made the subject of a valuable memoir by Dr. Hooker and Mr. 
Binney. So far as the longitudinal sections are concerned, the results 
obtained correspond closely with those already arrived at by these 
two authors, except that a modified form of lagenostome is shown to 
have existed at the apex of the nucleus. The transverse sections show 
that the two layers of the testa, an outer soft parenchymatous exotesta 
and an inner sclerotesta, present some striking features. The exterior 
of the latter has exhibited three "principal, acute, prominent, longi- 
tudinal ridges, between each two of which are three intermediate 
ones, the centre of these three being rounded, and the two flanking 
ones acute. The internal cavity of the endotesta is prolonged like a 
narrow fissure only into each of the three principal ridges. The 
ordinary sandstone specimens of Trigonocarpum olivceforme commonly 
seen in cabinets do not represent, as has hitherto been supposed, the 
