PLATE CXXIa. 
Gomphooeras impar. Hall. 
See Plate 120. 
1. Venti’al view of an individual jireserving the chamber of habitation and a large part of the septate 
tube, showing the characters of the siphuncle as exposed in the process of weathering. Near 
the grand chambei-, there were several veiy shallow air-chambers, as indicated by the beads of 
the siphuncle. 
Corniferous limestone. ColumJms, Ohio. 
Gomphooeras crenatum. 
Page 33. 
2. Lateral view of the fragment, showing the form of the tube, and the furrows of the crenulated band, 
which are continued over the walls of the air-chambers. 
Corniferous limestone. Delaware county, Ohio. 
Gomphooeras plenum. 
Page 33. 
3. Latei-al view of a specimen which preserves the chamber of habitation with about fifteen attached 
air-chambers, showing the form of the shell and depth of the air-chambers, of which there are 
several shallow ones near the grand chamber. 
4. Id. Septum showing the circular transverse section of the tube and the position of the siphuncle. 
Corniferous limestone. Colwnbus, Ohio. 
