PLATE III. 



Fig. 



la. Lytoceras confusum, S. S. Buckman,. tvro-thirds natural 

 size. Zone of Harpoceras Sowerlyi, Bradford Abbas, 

 Dorset. Collected by my father. 



\h. The same, showing ventral area and the somewhat trian- 

 gular aperture. 



2a. Lytoceras confusum, S. S. Buckman, young specimen 

 Sowerbyi zone, Bradford Abbas. Side view showing a 

 portion of the mouth-border. My collection. 



2J. The same, showing the ventral area and the difference in 

 the shape of the aperture in youth. See text. 



Za. Occotranstes f MJwridgii, nobis. Zone of Rarpoceras 

 Sotverhyt, Bradford Abbas, Dorset. 



3b. The same, showing ventral area and aperture. 



