64 Trans, Acad. JSci. of St. Louis. 



as usually exposed may be due to a weathered condition, but 

 this could only be determined by extensive excavations. The 

 fossils are most abundant, in fact are almost wholly restricted 

 to the upper ^ve or six feet of the bed, just below the thin 

 band of impure limestone, — bed No. 3 (Weller). 



It is usually possible to recognize the fossils from the 

 Chonopectus sandstone, by their lithologic characters alone. 

 They could only be confused with those of bed No. 5 (Wel- 

 ler), but the Chonopectus sandstone is usually of a deeper 

 yellow color, often reddish, and is softer than bed No. 5. In 

 the upper yellow sandstone. No. 5, the cavities remaining from 

 the solution of the shells are usually preserved, the greater 

 density of the rock not allowing them to be closed by pressure. 



The writer is under the greatest obligation to Prof. I. C. 

 Russell of Ann Arbor, Michigan, for the use of the types 

 and other specimens of Burlington fossils preserved in the 

 *• White Collection " in the University of Michigan. These 

 specimens have been loaned for study with the utmost gener- 

 osity, and without the hearty co-operation of Prof. Russell the 

 present paper could never have been prepared. A large pro- 

 portion of the illustrations here published have been drawn from 

 the type specimens in the University of Michigan collection. 



Prof. Samuel Calvin, state geologist of Iowa, has also 

 loaned a small collection of Kinderhook fossils from Burling- 

 ton. Acknowledgment is also due Dr. H. F. Bain, assist- 

 ant state geologist of Iowa, for the helpful encouragement 

 he has given during the prosecution of the work. 



Description of Species.* 



ECHIXODERMATA. 



A few detached joints of crinoid stems have been observed 

 in the Chonopectus sandstone, as well as a single form which 



^ * The bibliographic references have been omitted from these descriptions. 

 For these the reader is referred to Bulletin 153, U. S. Geological Survey, 

 " A Bibliographic Index of North American Carboniferous Invertebrates," 

 by Stuart Weller. Washington, 1898. In the case of species referred to a 

 different genus in the present paper than in Bulletin 163, a reference is given 

 to the Bulletin. 



