The American Geologist, Vol. XXVIII. 
Plate XXVIl. 
Fig. 1. Mass formed of two unequal growths of Fistulipora extending through the upper six 
feet of Clinton upper limestone into the base of the Rochester shale. Dimensions 32x11 feet. 
Fig. 2. Remnant of eioded mass, showing shale encroachment, pdckttings, etc. Spaces 
between limestone layers formed by removal ot shale. A — 10 inch stratum. Hexed in con- 
formation to removed part of the mass; B — thickened stratum at side of Fistuliporid head ; 
C — oldest remaining portion of the mass; I) — Rochester shale. Breadth 18 feet. 
Fig. 3. An oblique growth which probably started in the depression at B. The line of 
growth, C, is made of imbricating dome-shaped shells of Fistulipora. The oblique axis is 
fully 12 feet long. A — Rochester shale. B — portion chiefly Tribolites and Cephalopods. 
REEFS IN THE GENESEE RAVINE AT ROCHESTER. 
Above the R. W. & O. R. R. bridge. 
