PLATE XXXIII. 



Zone of Aegoceras Henleyi. 



Fig. 1. Aegoceras Henleyi, Sowerby. Lateral view of a perfect specimen, showing 



the change of form which took place in 

 middle-age period of this remarkable 

 species. 



2. — — - — Front view of the same shell. 



3. — — — Siphonal area of the same shell. 



The outer whorl of this fossil is the true Ammonites Henleyi, Sow., ' Min. Conchology,' 

 pi. clxxii, and the inner whorls here in situ in this rare specimen are clearly the 

 Ammonites latecosta, Sow., ' Min. Conchology,' pi. dlvi, fig. 2. This specimen I 

 obtained several years ago from the green Ammonite bed, near Charmouth, Dorsetshire 

 and since I have had three other less perfect specimens from the same stratum, all, how- 

 ever, show the same anatomical characters which are so well displayed in the beautiful 

 drawing Mr. Gawan has given of this Ammonite. 



