• Transcribe
  • Translate

Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898

Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 90

More information
  • digital collection
  • archival collection guide
  • transcription tips
 
Saving...
[page]89.[/page] 1855; P. flemingi, P. calhounianus, and P. korrinekianus, by Geinitz in 1866. Shell moderately large, breadth in well preserved individuals exceeding the length, greatest width at hinge line; front and forward part of lateral margins regularly curved; ears large, compressed, wrinkled. Dorsal valve concave usually flattened in posterior region; two ridges passing from region of beak to ears. Surface of this valve without spines but with radiating costae and concentric lines of growth. Ventral valve as in most members of this genus extremely convex, being most convex posterior to the middle, descending abruptly to cardinal angles, beak incurved. The only tendency in the way of a mesial sinus is a flattening of the valve along the median.
 
Scholarship at Iowa