386 PALEONTOLOGY OF ILLINOIS. 



The figure and description given of this species in the 2d vol. of this Report, 

 p. 431, pi. xxxvii, fig. 1, are imperfect, being made from the only specimen 

 found at the time. Better specimens now on hand show that this fern evi- 

 dently belongs to the genus Neuropteris, not only by its nervation, but by its 

 ramification and the position of the leaves on the rachis. The species nearest 

 to this is Neuropteris crenulata, Brgt., easily distinguished by its elongated nar- 

 rower leaves, with crenulate rather than toothed borders, and the thickness of 

 its veinlets. Our fig. 5 represents a specimen whose upper leaflets, scarcely 

 dentate, have the surface wrinkled around, and marked by points of irregular 

 size, placed without order, which resemble traces of fructification, the epider- 

 mis appearing as if it had been perforated by glomerules of spores placed under 

 it. This peculiar appearance may result from the process of maceration. It 

 is too obscurely marked to merit more than a passing mention. 



NEUROPTERIS RARINERVIS, Bunb. 



PI. viii, fig. 1 to 6. 



The specimens figured 1 to 4 on this plate, from the concretions of Mazon 

 creek, bear round leaflets, apparently attached on both sides of a secondary 

 rachis, as are generally the pinnules of a Neuropteris. According to this ap- 

 pearance we should have not only to consider these leaves as representing a 

 new species, but also to accept the genus Nephropteris or Cyclopteris for their 

 classification. But I think that the parts represented in fig. 1 and 2, are not 

 fragments of a secondary pinna with alternate pinnules attached to it, but only 

 parts of primary pinnae with the basilar leaflets of the secondary pinna- at- 

 tached to them, in the same way as such leaflets are attached along the rachis 

 in fig. 6, which represents a fragment of pinna of Neuropteris rarinervis. 



This remarkable specimen is also from Mazon oreek. As is easily seen, it 

 shows a primary rachis with the base of its diversions marked by the remains 

 of the secondary branches and the two basilar leaflets on each side of them. If 

 this branch were longer, we should see these basilar leaflets more and more en- 

 larged, becoming round farther down, and then showing the same forms as we 

 see on fig. 1 and 2. In vol. 2, p. 429, in a foot-note of this Report, mention 

 is made of a specimen from Newport, R. I., which bears on the same part of a 

 frond two round cyclopteroidal leaflets attached at the axil of secondary pin- 

 nae, while the same pinnae bear true neuropteroidal oblong pinnules, with a 

 medial nerve. As this specimen elucidates the position of the two kinds of 

 leaflets, and as it is the only one found as yet elucidating this peculiar differ- 

 ence, I have figured it fig. 5, as affording the most conclusive representation of 

 the unity of both the genera Neuropteris and Nephropteris. This figure, I 



