140 Transactions of the Society. 



Our knowledge of these is due to the work of many investigators, 

 among whom the late Dr. Stur, of Vienna, and my friends, Professor 

 Zeiller, of Paris, and Mr. Kidston, of Stirling, must be specially 

 mentioned. 



On fronds of the genus Pccopteris, in particular, we find very 

 characteristic fructifications, with the sporangia ranged in definite 

 sori, the members of which are often more or less fused together, 

 and are usually without a typical annulus. Such fructifications 

 are characteristic of the small tropical family Marattiacea? among 

 recent Ferns, a group which evidently played a much more im- 

 portant part in Palaeozoic times. The modern Marattiacese are 

 often large handsome Ferns, but not so large as their ancient allies, 

 which attained the stature of trees. The anatomy of their tall 

 stems is known in many cases (the numerous species of Psaronius), 

 and proves to have been extremely complex, entirely Fern-like in 

 character, and resembling that of recent members of the Order 

 Marattiacese. Thus the anatomical evidence strongly supports 

 the conclusions drawn from the reproductive organs, and there can 

 be no doubt that in many, at least, of the species of Pccopteris, 

 we have to do with true Ferns, referable to a definite living family. 

 Among the fructifications the type with circular sori, now only 

 represented in the genus Kaulfussia, was common in the Car- 

 boniferous Marattiacere, as in the groups Asterotheca, Scolccopteris, 

 and Ptychocarpus (fig. 32), genera founded on reproductive cha- 

 racters, and distinguished in part by the degree in which the 

 sporangia of a sorus were united to one another. Among the 

 Pccopteris fronds there were others which bore fructifications less 

 clearly Marattiaceous, but in none of them is there anything to 

 oppose the inclusion of the plants among the Ferns. In the case 

 of Scnftcnbcrgia the sporangia recall those of the recent Schizre- 

 acere, of which the Climbing Ferns (Zygodium) are familiar ex- 

 amples. The fructification known as Oligoearpia, resembling that 

 of Gleicheniaceous Ferns, occurs on fronds both of the Pccopteris 

 and the Splicnoptcris type. At least eleven genera of fructifications 

 have been referred to the fronds of different species of Sphcnop)tcris. 

 Some of these were no doubt really the reproductive organs of 

 Ferns, as Oligoearpia and Coryneptcris ; others, as Umatoptcris, are 

 doubtful ; while some, as Crossotheca and Calymmatotheca, were in 

 all probability of a totally different nature. 



Good examples of typical Fern-fructification are often met with 



EXPLANATION OF PLATE II. 



Fig. 3. Neuropteris heterophylla. Portion of frond, slightly enlarged. 

 „ 4. Seed of the same plant, showing two characteristic pinnules, attached to the 

 stalk bearing the seed, x 2 diam. Figs. 3 and 4 from photographs 

 kindly supplied by Mr. R. Kidston, F.R.S. 



