140 
SMITHSONIAN INSTITUTION 
comparison with the preceding species, to show the extremes in general form 
of calyx, variation in the forked radials, the orals covering the central space 
of the tegmen, and a detail of the arm clusters. 
5. angulatus Conrad, the type, is from the Rochester shale, and S. gemmiformis Hall, 
plate SI, figures 17-19, a species of wide distribution and in many ways the opposite of the 
former, was described from the same horizon and locality, as well as from the Waldron for- 
mation of Indiana, and is also found at Newsom, and other localities in Tennessee. 
