PLATE HI. 



Fig. 



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

 size. Zone of Harpoceras Sowerlyi, Bradford Abbas, 

 Dorset. Collected by my father. 



11. 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. 



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

 the shape of the aperture in youth. See text. 



Sa. Occotranstes? Etheridgii, nobis. Zone of Harpoceras 

 Sowerlyi, Bradford Abbas, Dorset. 



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



