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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 'J2 



compartments. I'hese cages are securely anchored, and every pre- 

 caution has heen taken to make sure that the moUusks 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 

 better idea of them may be 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 Ccriun incanuui from 

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

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

 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 



