312 Studies A^nong Alollusks. [zoe 



Bembidium bifossulatum. In wet sand. 

 Bembidium crurale. In wet sand. 

 Bembidium approximatum. In wet sand. 

 Bembidium ephippiger. In wet sand. 

 Bembidium erasum. In holes in wet sand. 



The ocean beach at this place is" poor in MoUusca, but we find 



Nuttalh 



Califi 



STUDIES AMONG MOLLUSKS— INSTINCT AND 



GENERA. 



by henry HEMPHILL. 



Helix (Glyptostoma) Newberryana W. G. Binney. 



The study of this moUusk, its shell and habits, supplies us with 

 some puzzling and interesting facts that are worthy of close and 

 careful investigation. 



We are told by Mr. W. G. Binney, the highest authority on our 

 American land shells, that the animal inhabiting this shell is a " true 

 Helix," while I might add the shell it moulds and forms is the shell 

 of a true Zonites. Mr. Binney at first, 1859, described the shell as 

 a Helix, subsequently, 1869, he removed it to the genus Zonites, 

 but later, after the study of the soft part from specimens I sent hiin 

 from San Diego, California, he removed it again, putting it back 

 into the Helicidae, making for its reception the genus Glyptostoma. 

 The late G. W. Tryon placed this shell in the genus Macrocyclis. 



Now we have been taught and led to believe that animals per- ' 

 form all their functions of life by instinct, and instinct is supposed 

 to be unerring in its action, being directed and governed by laws 

 over which the animal has no control. If our division of these 

 animals into genera is based on true and natural principles, and if 

 genera really exist in nature, then good logic would lead to the 

 conclusion that, as each genus is separate and distinct from the 

 others, then equally as distinct must be the generic instinctive im- 

 pulses, for they partially serve to define genera, as well as modifica- 

 tions in the structure of the animals. If this is true, it would be 

 reasonable to suppose that all the members of a genus would be 



equally stimulated or animated by this generic impulse, and hence 



