86 
BULLETIN OF THE LABORATORIES 
specimens indicate interrupted growth in the zoarium. About 7 cells 
occupy a length of 2 min. 
Locality and position. Bald Hill and Flint Ridge. 
Among the Flint Ridge collections corals are exceedingly rare 
and only one species has so far been recognized, belonging to the fol- 
lowing genus. 
Genus CYATHAXONIA, Michelin. 
Single polyp cells, with diaphragms, the invaginated centres of 
which form a solid central axis, the cristiform columella. Radial 1 am- 
ellse well developed, terminating as superficial carinations on the con- 
ical centre of the diaphragms. (Rominger, Fossil Corals, Geol. 
Surv. Mich. Vol. Ill, p. 96). 
Cyathaxonia prolifer a, McChesney. 
{Plate VIII, Fig. 15, <2, b, c.) 
Coral conical, nearly straight, or curved below; epitheca thin, 
marked by distinct vertical ridges locating the apertural and lateral 
gaps distinctly; calyx nearly circular, deep; radial lamellae 20-28, 
beginning as carinations at the mouth of the calyx, slowly enlarging 
below and ending as ridges on the invaginated diaphragms ; alternat- 
ing with these lamellae are carinations or secondary lamellae, which 
reach scarcely more than half the distance down the calyx, and there- 
fore are seen only in well preserved specimens ; the columella com- 
pressed laterally, the larger axis in' line with the apertural and central 
gaps, very prominent. 
Largest specimen so far found 22 mm. long, and 17 mm. wide at 
the mouth of the calyx ; the calyx is 13 mm. deep, the columella pro- 
truding into the same fora distance of 7 mm; the columella is 2.7 
mm. wide below, and about i mm. thick. The columella is not al- 
ways so well preserved. 
Locality and position. Flint Ridge and Bald Hill. 
During the publication of these pages I learned that Mr. E. O. 
Ulrich was engaged on a similar list of bryozoa from the base of the 
Coal Measures at Seville, Illinois, for the Illinois Geol. Surv. Vol. 
