KIDSTOX: THE FLORA OF THE CARBONIFEROUS PERIOD. 193 



The exannulate form of fructification is illustrated by several 

 genera, Mhich are characterised by the form and arrangement of 

 the sporangia. Among these may be mentioned RenauUia Zeiller, 

 where the small oval sporangia are situated on the veins towards 

 the margin of the pinnules (Plate XXVIII., 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 Dmuvxi 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. 



NEUROPTERlDEiE. 



The most important genus of this family is Neuropteris 

 Brongt. (Plate XXVIII. , fig. 3. Neuropteris gigantea Sternb.). 

 The pinnules ai'e 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 off lateral divided veinlets (Plate XXIX., fig. 4). On 

 some species of Neuropteris, possibly on the majority, between 

 tlie points of insertion of the lateral pinnse or towards the base of 

 the frond, immediately below the pinnse, the main rachis bore 

 reniform or orbicular pinnules (Plate XXVIII., fig. 3, 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 Neiiropteris is 

 imperfectly known, but in the case of Ne^iropteris heterophylla 

 Brongt. it was borne on long pedicels which terminate the pinnse. 



