GEOLOGY OF LA SALLE COUNTY. 00 



LIST OF FOSSILS FROM COAL MEASURES 

 AXD CALCIFEROLS. 



We have been shown a curious specimen said to be 

 from the St. Peters, resemblino- the inner side of a 

 spare-rib. three ribs being represented. It was a 

 frag-ment only, and one mig-ht ofuess over it to the end 

 of time. Some day some one will stumble on a larger 

 and more perfect specimen, and then its relations may 

 become manifest. AYe occasionallv find in it, north 

 bluff of Illinois, two miles west of Ottawa, and river 

 bluff, one mile southwest of same, semi-elliptical 

 masses made up apparently of concentric layers stand- 

 ing- erect, rounded end down, as if thev had been 

 dropped into the St. Peters when it was soft. These 

 are not numerous, but frequent enoug-h to lead one who 

 sees, to ask what they are. The question awaits an 

 answer. See Plate 11. , Figf. 14. 



The coal measures are very prolific of fine speci- 

 mens, both the limestones and the shales, especially 

 some ('f the black ones. The species thus far de- 

 scribed are as follows: 



riollusks. — Brachiopoda, shells having curious 

 hook-like or loop-like appendages on the inside, Mar- 

 tinia 'spirifer ) piano conversa; Spirifer Kentuckensis, 

 S. Cameratus, S. Carbonaria, Terabratula bovidenis, 

 Achyris subtilit^, Athyris Ro3fisii. Chonetes Millep- 

 unettate, C. Mesoloba, C. Flemingii, C. Granulifera, 

 Discina nitida, D. Subtrijonalis, L. Capuliformis; Pro- 

 ductus Xebrascensis, P. punctatus, P. S3'mmetricus, 

 P. inflatus. P. longispinus. Lamellibranchs; in struct- 

 ure resembling the mussel or clam; P. costatus, P. La 

 Sallensis, P. Milberanus; Or this 'Hemipronitis) La 

 Sallensis, Orthis H. Crasus, Orthis H. Carbonaria, 

 Orthis Pecasi; Retzia punclulyeraa, Rhynchonetta 



