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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 72 



compartments. These cages are securely anchored, and every pre- 

 caution has been taken to make sure that the mollusks will be confined 

 within them, and that no extraneous individuals can find entrance. 

 The cages are arranged as shown in the following diagram, and a 

 lietter idea of them may l^e formed from the photograph (fig. 50). 



Fig. 49. — Diagram showing arrangement of cages. 



Cages No. 45 and No. 46 are of the same size as those last men- 

 tioned. In cage 45 were placed 183 young of Cerion incanum from 

 Key West, in order to determine what percentage of these will reach 

 maturity. In cage 46 was placed an abnormal specimen of Cerion 

 viaregis. This had a spiral keel, which may be the result of an injury, 

 although Doctor Bartsch was unable to discover any sign of it. 

 With it was also placed a normal specimen of Cerion viaregis in order 

 to determine if this character might be transmitted to offspring. 



In addition to these, five groups of cages were made which have the 

 same size as the four unit cages, but they have only one partition in 



