PLATE XXIX. 



Zone of Aegoceras armatum. 



Aegoceras armatum, Sowerby. An aged specimen, natural size, showing the large 



dimensions of the spines on the body-chamber and 

 the comparative smallness of the spines on the inner 

 whorls. This specimen was obtained at Lyme 

 Regis thirty years ago, and was long the adorn- 

 ment of a private collection. It now belongs to 

 the Museum of the Royal School of Mines, and I 

 have the pleasure of having it figured for the first 

 time. 



