90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I39 



Pa Re 



D. Aphelesia bipartite/, (Brocchi) 41 



Figs. 18-25. Sections through the valves of a full-grown adult, X 2 . 

 British Museum (Natural History) not numbered, showing sockets 

 and teeth. Sections respectively from the beak of the pedicle valve: 

 (18) i.omm., (19) 1.6 mm., (20) 2.0 mm., (21) 2.6 mm., (22) 

 2.8 mm., (23) 3.2 mm., (24) 3.6 mm., and (25) 4.0 mm. 

 Miocene, St. Lorenzo, Tuscany, Italy. 

 Photographs of figures 10-15 and 18-25 by permission of the Trustees of the 

 British Museum (Natural History) through Dr. H. M. Muir-Wood, Deputy 

 Keeper, Department of Palaeontology. 



