PLATE IV. 
All figures natural size. 
Illustrations of the compound coral Cyathoyhyllum calvini Thomas; 
from the Niagaran dolomitic limestone, Scotch Grove township, Jones 
county, Iowa. 
Figs. 1, 2. Broken fragments showing in cross section the arrange- 
ment of the septa and the dissepiments. Note also the close ap- 
proximation of the corallites. 
Fig. 3. A small portion showing the wrinkled epitheca. 
’ Figs. 4, 5. Stems showing budding; the buds are from two to four 
millimeters in diameter and have well developed septa and dis- 
sepiments from the beginning. 
Fig. 6. A fragment preserving the calyx. 
Fig. 7. A part selected to illustrate the general appearance of the 
coral. Note the edges of the septa and the vesicular structure where 
the thin epitheca has been removed. One or two buds may be 
seen and in the lower center may be seen a fragment of a minute 
braehiopod shell mentioned in the paper. 
This specimen is designated as the type. 
All the specimens here illustrated are preserved in the Geological 
Museum of the State University of Iowa. 
