PLATE CXXI. 



GoMPHOCERAS EXIM1UM. 



Page 32. 



See Plate 120. 



Fiy. 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 siphunele. 



Corniferous limestone. Columbus, Ohio. 

 Pig. 2. A fragment of the septate portion, in which the siphunele has been partially uncovered by the 

 removal of a portion of the filling of the air-chambers. 



GOMPHOCERAS MITRA. 

 Page Z'i. 

 See plate 120. 

 Fig. 'S. A large septate fragment with the siphunele as exposed in the process of weathering of the air- 

 chambers, showing the moniliform character of the siphunele, and the furrowed cinctures of its 

 tube. 



Corniferous limestone. Columbus, Ohio. 



