NATURAL HISTORY STUDIES ON THE ELORIDA KEYS 

 AND THE WEST INDIES 



By PAUL BARTSCH. 



Curator. Pn'isioii of MoIIusks. L\ S. AUifiomil Miisruni 



THE CERION BREEDING EXPERIMENTS 



Eifteeii years ago at the invitation of Dr. Alfred (j. Mayor, the 

 then Director of the Marine Biological Lahoratory of the Carnegie 

 Institution, I joined his expedition to Andros Island, Bahamas. I was 

 to devote my attention to the general invertebrate fauna of the region. 



In looking over the general field, particular])- that of moUusks in 

 ])reparation for this work, I decided to let alone one group of these 

 creatures, namely, members of the genus Cerion. for it was a some- 

 what tacit understanding that peoi)le who had devoted themselves 

 to this group had l)ecome more or less hopelessly entangled in it, and 

 some were even considered as having become slightly locoed. 



The old saying about a certain group of individuals stepping in 

 where angels fear to tread, prt)ved again to he an estalilished fact, 

 for shortly after landing at the White House on South Bight, Andros 

 Island, I found myself picking up what I later named Cerion 

 casablaiicac, and that was the beginning of many years of work, for 

 I am still at the problem and will probably continue to be for some 

 time to come. 



A little l)efore going to the Bahamas, I had worked over the col- 

 lection made by Owen Bryant on these islands, which was described 

 by Dr. Dall.^ That bit of work enabled me to understand why it 

 took a man of Dr. Dall's standing to have the courage to describe 

 new species of Cerions then. At that time it was the generally as- 

 sumed belief that Cerions were a most plastic group, readily changing 

 under the influence of changes in environment. In a general way we 

 lielieved that a dry year might afl:'ect the food supply and activity 

 and growth of individuals, and young born under such conditions 

 would probably show the efl^ect by having smaller shells or slightly 

 difi:'erent sculpture, or other characteristics that might dififerentiate 

 them from individuals born under more propitious circumstances. 

 It is a fact that at the beginning of our studies, very little was known 

 about Cerions except descriptions of shells and that they usually 

 occurred in large numbers wherever found. 



' Smithsonian ^[isc. Coll., Vol. 47, Pt. 4, Publ. No. 1566, 1905. 



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