kidston: the flora, of the carboniferous period. 193 
The exannulate form of fructification is illustrated by several 
genera, which are characterised by the form and arrangement of 
the sporangia. Among these may be mentioned Renaultia Zeiller, 
where the small oval sporangia are situated on the veins towards 
the margin of the pinnules (Plate XXYIII., fig. 4). They open 
by a longitudinal cleft. The fruiting pinnules are little modified 
from those of the barren frond. 
In Urnatopteris Kidston the barren (Plate XXIX., fig. 1) 
and fertile (Plate XXIX., ngs. 2 and 3) fronds are dissimilar, 
that is, only some of the fronds bear sporangia, and on these 
the pinnules are entirely deprived of the limb — the sporangia 
being arranged in two rows, one on each side of the rachis. 
The sporangia are pointed-oval, and open at the summit by a 
small round pore (Plate XXIX., fig. 6). Each sporangium is 
free, but in their structure they have considerable resemblance 
to the sporangia of Danma only in that genus the sporangia 
are united to each other to form a synangium. Though I only 
mention these two Sphenopteroid exannulate types, others are 
known. 
NEUROPTERIDEiE. 
The most important genus of this family is Neuropteris 
Brongt. (Plate XXYIII., fig. 3. Neiiropteris gigantea Sternb.). 
The pinnules are generally more or less oval or tongue-shaped, 
and articulated to -the rachis, from which they are easily 
detached. Each pinnule had a central vein, from which are 
given ofi* lateral divided veinlets (Plate XXIX., fig. 4). On 
some species of Neuropteris, possibly on the majority, between 
the points of insertion of the lateral pinnae or towards the base of 
the frond, immediately below the pinnae, the main rachis bore 
reniform or orbicular pinnules (Plate XXVIII., fig. 3, a, a), 
sometimes of large size; these, before their true origin was known, 
were supposed to belong to a distinct plant, and were named 
Cyclopteris by Brongniart. The fructification of Neuropteris is 
imperfectly known, but in the case of Xeuropteris heterophylla 
Brongt. it was borne on long pedicels which terminate the pinnae. 
