PLATE I. 



Fig. 



la. Amaltheus? Stephani, nobis, two-thirds natural size, 



showing the fine mouth-border, I believe, from the zone 



of Harpoceras Sowerlyi, from near Sherborne, Dorset, 



collected by my father. The greater portion of the test 



is well preserved. 

 \b. The same, showing ventral area ornamented with small 



keel and the aperture. 

 20. Cosmoceras Hollandae, nobis, natural size, zone of Har- 



poceras Murchisonae, under cliff at Burton Bradstock, 



Dorset, my collection. 

 2b. The same, showing the ventral area with the channel and 



aperture. 



