﻿NO. 7 SMITHSONIAN EXPLORATIONS, I926 83 



also found a number of quite young shells, too young to determine 

 their relationship at this time. Dr. Bartsch therefore refrained 

 from seriously disturbing the sand for fear of exposing these small 

 creatures to unfavorable stresses. 



Island 2. In this were planted, 2 years ago, 25 Cerion incanum 

 and 25 Cerion chrysalis. Last year 11 of the Cerion incanum wfere 

 found dead and this year 4 dead and i living, accounting for 16 

 of the planted specimens. Of the Cerion chrysalis, 12 were found 

 dead last year ; to this were added 4 this year and 2 living individuals, 

 which accounts for 18 of the 25 planted. Here, too, small young 

 were in evidence. 



Island 3. On this island were planted, 2 years ago, 25 Cerion 

 incanum and 25 Cerion niummia. Last year 16 dead of Cerion incanum 

 and this year 2 dead and 5 living were recovered. Of Cerion niummia 

 17 were found dead last year and i this year, and i living. All 

 but 2 of the Cerion incanum are therefore accounted for in this 

 island. Here, too, some young were present, and the interesting 

 observation was made of finding a specimen of Cerion incanum 

 mating with a Cerion munimia. 



Island 4. Here were planted, 2 years ago, 25 Cerion incanum and 

 25 Cerion tridentatum. Of these, 13 Cerion inca)\um were found 

 dead last year and 3 this year, and 2 living. Of the Cerion tridentatum, 

 10 were found dead last year and 3 this year, and 10 were living. 

 No young were observed. 



In the 8 small islands, all the adults seem to have died, but 

 small young are present in some, which makes it wise to leave them 

 undisturbed for another year as these may prove to be the desired 

 hybrids. However an additional marked specimen of Cerion incanum 

 and Cerion viaregis were added on each island. 



Last year some of the old wooden cages were cut down to mere 

 4-inch base boards which were partly buried and fastened securely 

 to the ground. To the free edge of each, which projects some 

 3 inches above the ground, a narrow strip of monel wire was 

 tacked, bending inward to prevent the escape of the mollusks. 



In each of these cages a specimen of Cerion incanum and Cerion 

 inaregis was placed. Upon examining these inclosures this year, most 

 of the shells were found dead and many were crushed, the damage 

 probably having been done by rats. Each of these 75 cages were re- 

 stocked with a marked specimen of Cerion incanum and Cerion 

 viaregis. 



