256 GEOLOGY OF ILLINOIS. 



like an elongated pecan nut, the relations of which have not yet been 

 determined. These limestone concretions have been found in Fulton 

 and Schuyler counties overlaying coal No. 3, and affording most of the 

 species of fossil shells obtained from it here 5 so that there seems scarce- 

 ly a doubt but that it here represents the horizon of that coal. It is 

 quite probable that in the eastern, and especially in the south-eastern 

 portion of the county, coal No. 3 may be found sufficiently developed to 

 be worked to advantage. The shale and sandstone above this coal, 

 No. 1 of the foregoing section, we only saw in the vicinity of Colchester, 

 w T here about ten feet in thickness of sandy, ferruginous shales overlay 

 the limestone concretions above mentioned. No. 4 of the foregoing sec- 

 tion is well exposed on the ravines leading into the east fork of Crooked 

 creek, west of Colchester, but it is everywhere a sandy shale, with some 

 thin layers of sandstone, but affords no material of any economical val- 

 ue. The calcareous shale associated with the limestone in No. 2 of the 

 above section is, at some points near Colchester, quite full of small fos- 

 sil shells, among which the Spirifer plano-convex us was the most abund- 

 ant, associated with S. lineatus, Chonetes mesoloba, Productus muricatux, 

 Pleurotomaria GrayvillensiSj a small Macrocheilus, and fragments of a 

 Nautilus. 



No. 5 of the above section forms the roof of the Colchester coal, and 

 is a true clay shale at the bottom, arid locally quite bituminous, becom- 

 ing sandy higher up, and gradually passes into the sandy shales of No. 

 4. It contains ironstone concretions similar to those at Mazon creek 

 and Murphysboro, though ' usually not so perfectly formed, and they 

 contain fossil ferns of the same species found at those localities. The 

 shales also are filled with beautiful ferns, in a remarkably fine state of 

 preservation ; and this locality may be reckoned as one among the best 

 in the State for collecting these beautiful relics of an ancient vegetable 

 world. Two specimens of fossil insects and two or three species of 

 shells have been found associated with the fossil ferns at this locality. 

 The following list comprises all the species of fossil plants that have 

 been identified at Colchester to the present time: Neuropteris hirsut<( 7 

 N. tenuifolia, N~. rarinet*viSj Alethopteris aquilina, Callipteris Sullivantii, 

 Pecopteris squamosa, P. villosa, P. unita, P. plumosa, P. ckcdrophylloides, 

 Sphcnopteris irregularis, 8. trifoliata, Hymenopliyllites alatus, H. spin- 

 osus, H. splendens, H. Gutbierianus, H. thallyformis, Cordaites borassifo- 

 lia, C. angustifolia, Sphenophyllum Schlotheimii, 8. emarginatum, 8. cor- 

 nutum, Annularia longifolia, A. sphenophylloides, Asterophyllites equiseti- 

 formis, Calamites ramosus, C. approximatus, C. undulatus, Selaginites 

 uncinnatus, 8. carifolius, Lepidodendron diplotegioides, L. simplex, L. 

 obovatum, L. gracile, Ulodendron majus, U. elUpticum, Lepidophloios ol>- 

 cordatum, Lepidostrobus princeps, Lepldopliyllum auriculatum, ftigillaria 



