78 FLORA OF LOWER COAL MEASURES OF MISSOURL 



phimosa} Grenerally, however, the pimuiles are fully up to the typical size, 

 agreeing in form, nervation, and limb with the European species. A few 

 examples, from Pitcher's mine, show the pinnules rather more ci'owded, 

 larger, broader, and smoother, the lamina being hardly raised between the 

 nerves. This form, which approaches nearer than the other to P. pennce- 

 fontiis, should perhaps receive some distinctive appellation. 



Although a number of the specimens are fertile, the sporangia are not 

 sufficiently clearly preserved to give any important details as to structure 

 or arrangement. 



Localities. — Collected in fine specimens from Pitcher's bank, U. S. Nati 

 Mus., 5641, 5642, 5643, 5655, 5738, 5739, 5743; Owen's coal bank, U. S. 

 Nat. Mus., 5621, 5742; Gilkerson's Ford, U. S. Nat. Mus., 5740. 



PECOPTEBIS cf. ARBORESOENS (Schlotb.) BlOUgU. 



PI. XXXVI, Fig. 3; Pi. XLIV, Fig. 3; Pi. XL VII, Fig. 61 



Among the material last transmitted by Dr. Britts are several fragments 

 of Pecopteris, the size, form, and nervation of whose pimia? and pinnules 

 seem to be fairly comparable with tliose of Pecopteris arborescens as described 

 by Brongniart' and further differentiated by Zeiller.^ Portions of the pinnge 

 as well as the general form of the pinnules present even more strongly 

 the aspect illustrated by Zeiller* as P. cyathea (Schloth.) Brongn., but the 



' Since the preparation of this report and synonymy the writer has had the opportunity to 

 consult Mr. Kidston's most interesting and thorough elaboration of the Pecopteris plumosa (Artis) 

 Brongu., as the result of -which the identity of the Filicites 2>lumo3us with Sphenopteris crenata L. & 

 H., -S. caudata L. & H., Asjiidites silesiacus Goepp., etc., is very satisfactorily demonstrated. The 

 specific inseparability of the plant described by Artis from most of the material later described by 

 various authors as P. dentata is also evident. An inquiry into the geologic horizons of the jilumosa 

 forms, including S. crenata, A. silcsiaca, and the fine series from the Middle Coal Measures illustrated 

 by Kidston, seems, however, to show that, in general, in Europe as well as in America the delicate 

 plumose type is more characteristic of lower stages of the Coal Measures, while the more robust type 

 with broader, more obtuse pinnules and a stronger nervation is essentially characteristic of higher 

 beds. The writer is therefore fully convinced of the desirability of retaining a varietal distinction, 

 for the later form, illustrated in this report, whose differences from the forms illustrated by Kidston 

 are quite apparent. The form which I have treated as P. dentata should probably be designated as 

 Feco2>terin phitnosa vsbT. dentata, the combination proposed by Kidston in 1887, since it appears that 

 P. plumosa (Artis) Brongn. has priority over P. dentata Brongn. The very full synonymy given by 

 Kidston (Trans. Roy. Soc. Ediub., vol. xsviii, pt. 1, 1896, p. 205, pis. i-iii) includes the Jphlebia 

 adnata, which he shows to be x>eculiar to Pecopteris {Dactylotheca) plumosa. 



-Hist. veg. foss., p. 310, pi. cii, figs. 1, 2. 



' Fl. foss. houill. Commentry, p. Ill, pi. xi, tigs. 1, 2. 



^ Op. cit., p. 119, pi. xii, figs. 1-4. 



