GRAPHIC PRESENTATION OP RELATIONS. 129 



by Von Roehl under N. plicata 1 (= N. rectinervis, Kidst.) 2 from the Coal 

 Measures, and N. voltzii, Brgt., 3 and N. salicifolia, Fisch., 4 from the Per- 

 mian, with the phases often seen in the basal portions of some species of 

 Alethopteris, as, for example, .4. lonchitica, A. grandini, or Callipteridium 

 sullivantii. 5 



On the basis of their fruitings, which are either exannulate or with only 

 a rudimentary ring, as well as from the analogies of their structure, all 

 modern authors agree in considering a large number of Paleozoic species 

 with pecopteroid nervation as most nearly allied to the Marattiacese 

 among living ferns. 6 This conclusion is natural, in view of the known 

 antiquity of certain living marattiaceous genera, as well as the probable 

 long existence of the eusporangiate ferns in Paleozoic time before the 

 leptosporangiate forms appeared. 



Graphic Presentation of Relations. — The following diagram represents in 

 graphic form the general idea of development for a few genera; but it is 

 not to be understood that the relations of individual genera are sup- 

 posed to be in all cases as therein indicated, nor that the scheme is meant 

 to imply a presumed proof or even the existence of evidence sufficient 

 to form the basis of a proof. The lines should indicate in most cases a 

 common rather than a lineal descent. It must be remembered that such 

 a scheme is largely mere speculation. Many of the implied relations are 

 improbable as well as incompatible. Some suggestions embodied in the 

 chart constitute my only excuse for presenting it. 



Conclusions. — In the foregoing discussion of what may be regarded as 

 a tentative hypothesis for the line of descent of several of the living- 

 genera of Marattiacese from the Megalopteris stock, I have not presumed 

 to attempt a proof or demonstration among a body of forms whose fruit- 

 ing is essentially unknown; I have rather sought to bring together some 

 of the evidence in favor of what I consider a good working theory. Ac- 

 cording to this hypothesis, we may suppose that the pinnate Tasniop- 

 teridese, or a portion of that group (without prejudice of any important 



1. Foss. Fl. Steink., Westfalens, pi. xx, figs. 7, 8; pi. xiii, fig. 8. 



2. Trans. Roy. Soc. Ediub., xxxv, 1888, p. 314, figs. '-'-4. 



3. Hist., pi. lxvii. 



4. Kutorga, Verb. Euss. Kais. Min. GeselL, St. Petersb., 1842, pi. i, fig. 2. 



5. From the analogous characters of the nervation the genera Neuropteris, Odontopteris, Lesteya, 

 Dictyopteris, Neriopteris, Megalopteris, and Tcenioptens were included in the Neuropterid group by 

 Lesquereux in one of his last publications on the Carboniferous flow (Ann. Rep. Geol. Surv. Penna., 

 1886,pt.l,p.475). Renault (Cours. bot. foss., 3me annee) makes the Neuropteridece include Neuropteris, 

 Odontopteris, Dictyopteris, Alethopteris, Lonehopteris, Callipteridium, and Callipteris. More recently 

 Grand Eury (Geol. Pal. bassin houill. Gard., p. 286. construes the, tribe so as to contain AulacopU ris 

 (Mydopteris), Alethopteris. Callipteridium. Neuropteris. Dictyopteris, Odontopteris, Tamiopleris, and a 

 new pecopteroid genus, Parapeeopteris, intermediate in form between the neuropteroid Pecopteris 

 species and those of Neuropteris, with fructification after the fashion of Damea. 



6. See Renault, Cours. bot. foss., 3e annee; Stur. Carbon PL Schatzlav. Sch., ii; Zeiller, PL foss. 

 Autun Epinac; Kidston, Trans. Geol. Soc. Glasgow, vol. ix, p. 1. 



