550 Mr. Mises on some new Brazilian Plants 
the space between the true pericarpium and the cohering perianthium consists 
of a mass of long, transverse cells; excepting that upon the three placente, 
as well as on two longitudinal lines in the middle of each intervening space, 
the membranes appreach each other with scarcely any cellular tissue between 
them, and upon these lines the fruit easily separates (from its being necessarily 
weaker at those points as the capsule dries and ripens) into three broad and 
three narrow valves, without exhibiting any trace of those longitudinal nerves 
which usually form a distinct margin to capsular valves. In Dictyostega and 
the related genera there exists but a small quantity of cellular tissue between 
the true ovarium and adnate perianthium, and hence the capsule is almost 
membranaceous when ripe; but in a similar position to that exhibited in 
Orchidee, is to be seen only a single line where the two membranes closely 
approximate, and which in like manner sometimes become ruptured from a 
similar cause, when the capsule ripens, and hence the separation into three 
imperfect valves is effected not by any regular fissure, but by an irregular 
laceration of the adhering membranes at those points where they are not 
strengthened by intervening tissue. On comparing also the seeds of Pleu- 
rothallis pectinata with those of Dictyostega orobanchioides, there appears 
scarcely any difference between them either in shape or structure, both pos- 
sessing a diaphanous reticulated testa many times. larger than the nucleus: 
in Pleurothallis, however, the reticulations are much smaller and more 
regular, and the cells constituting the areolz are marked with spiral fibres 
bearing some resemblance to the spiral cells occurring in the leaves of that 
genus: on the other hand, the areolæ of the seeds of Dictyostega ave much 
larger, longer, more transparent, and destitute of fibres. In regard to the 
included nucleus, the two genera offer a striking analogy, as it is in both 
inverted, and suspended by an elongated base from the attenuated apex of 
the rostelliform seed, and in both presents its nipple-like apex towards the 
hilum. | 
Besides the points of resemblance already mentioned, these plants present 
in other respects a striking approximation to Orchideæ, especially to the 
section of Pleurothalleæ, which often possess a simple erect stem with im- 
perfectly developed leaves, and are not unfrequently destitute of the pseudo- 
bulbs, so characteristic of the tribe: they often exhibit also a regular six- 
