PLATE XXII 
Fig. 1. Eyidoceras proteiforme Hall. A, three transverse sections* of the 
type specimen at intervals corresponding to the distances between the 
centers of the sections; showing the rate of increase of the conch, siphuncle, 
and endocones. B, diagrammatic ventro-dorsal vertical section of the same 
specimen. See also fig. 1 on pi. XXL 
Fig. 2. Endoceras proteiforme Hall. Transverse section of same speci- 
men as fig. 2 on pi. XXI, with missing parts indicated by broken lines. 
See also fig. 2 on pi. XXIII. 
Fig. 3. Endoceras proteiforme Hall. Transverse section of same speci- 
men as fig. 2 on pi. XXV, with missing parts indicated by broken lines. 
See also fig. 3 on pi. XXIII. 
All specimens figured on this plate are from Middleville New York, in the 
Trenton limestone. 
