PLATE XXV. 
Zone of Jrietites BucMandi, superior. 
Fig. 1. Aegoceras planicosta, Sowerhy. Natural size. This specimen represents a 
large Am. Dudressieri, d' Orhigny, which 
is in reality the adult form of Aegoceras 
PLANICOSTA, Sow. This magnificent speci- 
men belongs to the Royal School of Mines, 
and was collected at Lyme Regis. 
2. — — — A portion of the outer lamina of the shell, 
showing lines and perforations highly 
magnified. 
, 3. — — — , Showing parallel lines formed by a fine 
punctated surface. 
