Plate VI. 



The Fusus longirostris Series {Pliocene). 



(All the specimens are in the collection of the Museum of Comparative 

 Zoology at Cambridge. The illustrations are reduced.) 



Page. 



Figs. 1-3. Fusiis longirostris, typical varieties (1217, 27797, '^222,) 52 



4. Fusus castelarquatensis (type, 27795) 54 



5-7. Fusus incequicostatus, showing progressive variation (1216, 1216, 



27795) 55 



(168) 



