230 PROCEEDINGS OF THE ACADEMY OF [1888. 



Ortkisina crassa Meek and Hayden, 1858. Proc. Acad. Nat. 



Sci. Phila., p. 260. 

 Orthis robusta Hall, 1858. Geol. Iowa, vol. I, pt. II, p. 713. 

 Orthis lasallensis McChesney, 1860. New Palseo. Foss., p. 32. 

 Orthis richmondi McChesney, 1860. New Palreo. Foss., p. 32. 

 Hemipronites crassus Meek and Hayden, 1864. Palse. Upper 



Missouri, p. 26. 

 Orthis crenistria Geinitz, 1866. Garb, und Dyas in Nebraska, p. 



46. 

 Hemipronites crassus McChesney, 1867. Trans. Chicago Acad. 



Sci., p. 28. 

 Hemipronites crassus Meek and Worthen, 1873. Geol. 111., vol. 



V, p. 570. 

 At the Pioneer mine several moderately larger specimens have 

 been obtained. This species has been more generally known as 

 Hemipronites crassus M. and H. It is a common and characteris- 

 tic fossil of the coal measures throughout Iowa and the contiguous 

 states, and presents many varietal phases. Hall's Orthis robusta 

 described from this state is unquestionably identical with this species. 

 There is also associated with the Des Moines specimens a smaller 

 form, about five millimeters in width, which appears to differ very 

 materially from any forms of S. crenistria examined. 



Spirifera camerata Morton. 



Spirifer cameratus Morton, 1836. Am. Jour. Sci., vol. XXIX, p. 

 150. 



Spirifer cameratus Meek and Worthen, 1873. Geol. 111., vol. V, 

 p. 573. 



Though a most abundant and characteristic species of the coal 

 measures of the west, this species is represented in the Des Moines 

 collections by only two specimens, one fairly good though somewhat . 

 crushed, and the other fragmentary, yet they exhibit distinctly the 

 peculiar fasciculated costse, as in the typical specimens. 



Spirifera lineata Martin. 



Spirijer lineatus Martin, 1809. Petrif. Derb. Coal Meas. 



Spirifer perplexa McChesney, 1860. New Palte. Foss. 



Spirifera lineata White, 1884. Geol. Rep. Ind. for 1883, p. 133. 



Pioneer mine; six or eight specimens were obtained, associated 

 •with Athyris subtilita. 



