PLATE XXXIV. 



Fig. 1. Aegoceras 



Zone of Aegoceras Henleyi 



Y ou n g &n4 JZird* 



2. 

 3. 

 4. 



5. 

 6. 



7. — 



8. — 



Lateral view, natural size. The 

 figures in this plate are 

 arranged to show that Aeg. 

 maculatum, Young = Aeg. 

 capricornum, Schloth, of the 

 Yorkshire coast, is the imma- 

 ture condition of Aegoceras 

 heterogenum, Young and Bird, 

 found in the same beds. 



Siphonal area of the same shell. 



Front view of do. do. 



Specimen in which the trans- 

 formation scene in the last 

 whorl has been nearly accom- 

 plished. 



Front view of the same fossil. 



Siphonal area, showing the re- 

 markable change in the ven- 

 tral area both in width, tuber- 

 cles, and ribs. 



Accurate tracing of the lobe- 

 line. 



Do. do. another 



specimen. 



All the specimens figured in this plate belong to the Leckenby collection, Wood- 

 wardian Museum, Cambridge. 



