PLATE CXXI. 
Gomphoceras eximium. 
Page 32. 
See Plate 120. 
Fig. 1. Ventral view of a medium sized specimen, retaining the test over the whole exterior of the tube, 
and showing the form of the shell and the broad gentle sinus in the lines of growth, indicating 
the position of the siphuncle. 
Corniferous limestone. ' Columbus, Ohio. 
Fig. 2. A fragment of the septate portion, in which the siphuncle has been partially uncovered by the 
removal of a portion of the filling of the air-chambers. 
Gomphoceras mitra. 
Page 32. 
See plate 120. 
Fig. 3. A large septate fragment with the siphuncle as exposed in the process of weathering of the air- 
chambers, showing the moniliform character of the siphuncle, and the fun-owed cinctures of its 
tube. 
Corniferous limestone. Columbus, Ohio. 
