410 
PALAEONTOLOGY OF ILLINOIS. 
be some error of description or of illustration of the European species, which 
is marked as having its surface entirely smooth, while the figure shows it cov¬ 
ered with points or rugose. 
Abundant in the shales of the coal at Morris. 
Mn 7 . 
■ fn ; 2. ■ 
Sphenopteris trifoliata, Brgt. Veg. Foss., p. 202. 
U! 1 // 
PI. 53, fig. 3. 
In the shales of Colchester; found by Prof. A. H. Worthen. 
Sphenopteris elegans, Brgt. Yeg. Foss., p. 172. 
PI. 53, fig. 1 and 2. 
Two fine specimen’s' of tffi^specios have been obtained from the concretions 
of Mazon creek; by Mr. M. S/'Hall. 
Genus HYMENOPHYLLITES, Gopp and auct. Ill. Geol. 
Rep., vol. ii, p. 436. 
In preserving this genus, with its characters too vaguely defined as it is in 
vol. 2 of this Report, p. 436, it would be advisable to subdivide it as follows : 
§ 1. HymenopJiyllites proper, containing species with a generally membra¬ 
naceous delicate frond, pinnately divided, the primary divisions alternate or 
dichotomous, decurrent on the rachis and ultimate lobes linear obtuse, either 
simple alternate or irregularly divided ; nerves percurrent pinnately branching, 
ascending, simple in each lobe. This section contains HymenophyUites and 
Trichomanitcs , Gopp. 
§ 2. Aphlebia , including species with fronds of various sizes and forms,gen¬ 
erally with a broad rachis and more or less irregularly divided, the divisions 
rather dichotomous or pinnatifid, entire or variously laciniate lobed, the lobes 
sometimes enlarged and recurved ; veins parallel and numerous from the base 
of the fronds, dividing in fascicles from the rachis in each primary division, 
and passing by subdividing, as simple veinlets to the point of each lobe. To 
this section are referable the genera Aphlehia, Schizopteris , lifrodea, JPachy- 
pliyllum , etc. auct.* 
*W. P. Stumper, in Pal. Vcg., makes for this section a new genus, Rhacophylhim. 
