PLATE III. 



Murchisoncv-zone. 

 Figs. 1 — 3. — Ludwigia Murchison^i (Soiverby). 



Fig. 1. — A typical specimen; test complete; middle age; showing the passage 

 of the ribs into mere lines of growth. Side view. Natural size. Bradford 

 Abbas, Dorset. My Collection. (Page 17.) 



Fig. 2. — Front view, showing plain ventral area. 



Fig. 3. — A specimen with slightly larger umbilicus, showing mouth border 

 with lateral lappet. It should be observed that the ribs continue well marked 

 right up to the mouth border. Natural size. My Collection. From near Half- 

 way House, Dorset. (Page 17.) 



Figs. 4, 5.— Ludwigia Murohison2e, var. obtusa (Quenstedt) . 



Fig. 4. — Side view of specimen without much shell but showing a tendency to 

 develop spines. Natural size. My Collection. From near Beaminster, Dorset. 

 (Page 17.) 



Fig. 5. — Front view, showing the coarseness of the ribs and the squareness of 

 the section. 



Figs. 6, 7. — Ludwigia Murchison^, var. Batlii, 8. Buckman. 



Fig. 6. — Side view. Showing small umbilicus and fine and numerous ribs. 

 Natural size. In my Collection. Probably from Bradford Abbas. (Page 18.) 



Fig. 7. — Front view, showing section. The keel is drawn too sharp and 

 prominent, and the ventral area should be flatter and rather more angular, thus 

 giving the shell a squarer appearance. 



