402 PALAEONTOLOGY OF ILLINOIS. 
?J/&2 • ? ^7cMp« . 
'/sO*Yc. 
Wm * ^ 
Pecopteris villosa, Brgt., Yeg. foss., p. 316. '-lob ?' 
/, fit 3 Jc^, a : wwsi if 
PI. 104, fig. 3. 
This species is the most abundant of all in the concretions of Mazon creek, 
which show it in its multifarious forms. The nervation does not appear to 
have been seen by European paleontologists. Brongniart does not give any 
details of it, and Geinitz indicates it as simple, or with veinlets forking once 
a~ T 
A 5 >7 , / \-r-i, only, which is totally at variance with its true nature. The concretions con 
tain numerous parts of the plant preserved in a state of partial ’maceration, 
either with pinnae whose substance is destroyed, and which have nothing left 
but the outlines of their leaflets, and the entirely free veins and veinlets ; or 
pinnae half preserved, one part of which bears leaflets with the villous epider¬ 
mis, while the other part has the veins and veinlets free of epidermis, and 
quite distinct. From the form of its pinnule, the multiple divisions of its 
pinnae, and of its veins, this Pecopteris is exactly similar to P. polymorpJia, 
Brgt., the veinlets dividing once or twice or more, according to the place and 
» / / ■ ( 
size of the pinnules. ' ' ■ 
Z 7 ^ A>y ■ / 
W * 1 i /*!<< l l : i . 
ty/L 
■ \-> 2 ^^ m&/A/ /m 
'? i . 3 '£■*-> // 
XC 
i y <■ i 
/. 
Pecopteris arguta, Brgt. (fruiting.) 
*(■ 
/■ZM.yU 
PI. xiii, fig. ] 2 and 13. 
The part of a pinna, as represented in the figure, bears leaflets, connate at 
the base, oblong, lanceolate obtuse, somewhat shorter, more pointed, and more 
distinct than is generally the case in sterile pinnae of this species. But as the 
nervation, as well as the crenulate-toothed borders of the leaflets, are similar to 
those of Pecopteris arguta , and as these peculiar characters are not known in 
any other species of the coal,I consider this specimen as representing its fruit¬ 
ing part, which was before unknown. The sori appear like inflated dots placed 
just at the point of the simple veins or rather like conical sori , with the point 
to the inside of the leaflets and the enlarged opening outside at the point of 
the teeth, as marked, fig. 13, enlarged. Their form is distinct; with a strong- 
glass they even appear filled with a pulverulent matter. According to the form 
and the position of these fruit-dots, the species resembles an Aspidium , and 
should be placed in the genus Aspidites, Gopp. Sterile pinnae of this species 
are not rare in the shales at Morris. 
