26 EXPERIMENTS IN THE BREEDING OF CERIONS. 



In May 1913 we observed that several dead Cerion shells, evidently 

 belonging to this colony, were occupied by small hermit crabs in the 

 neighborhood. 



In April 1914 we found that part of the ground occupied by this 

 colony had been burned over and quite a number of the shells destroyed. 

 Most of the living shells were in the fringe of live bay cedars. As we 

 did not deem this habitat quite suitable, we cleared the place thor- 

 oughly by pulling the cactus and cutting the grass. This exhaustive 

 search resulted in the recovery of 200 Cerion casablancce and 150 Cerion 

 viaregis and a single young tip. We planted all this material in a new 

 location, which will be referred to in the future as Colony I. 



In June 1915 quite a number of specimens were discovered in the 

 fringe of bay cedars bordering the west side of the original planting 

 which we overlooked in 1914. We left these undisturbed. 



In May 1916 we found that this colony had again been subjected to a 

 severe burning and it was doubted if anything had survived. 



No specimens were seen in 1917. 



In January 1919 this place was so heavily overgrown with Uniola 

 paniculata that it was impossible to see anything of Cerions that 

 might have escaped our collecting and the fire. 



THE LOGGERHEAD KEY COLONY I. 



This colony (consisting of 200 Cerion viaregis, 150 Cerion casablancce, 

 and a single tip which were transferred from Colony H in April 1914) 

 is located in the second meadow northwest of Colony E, in a coarse 

 calcareous sand plain having a good stand of Sporobolus virginicus, 

 the whole being fringed by bay cedars. 



The colony was doing well in June 1915, but in May 1916 we found 

 55 of the planted mollusks dead; of these 28 belonged to Cerion via- 

 regis and 27 to Cerion casablancce; 18 young individuals of various 

 sizes were also observed. 



In July 1917 we discovered some adult first generation Florida- 

 grown Cerions in this colony, but all were readily referable to either 

 Cerion casablancce or Cerion viaregis. Apparently no crossing had 

 taken place. 



In January 1919 we gathered up all the material discoverable in this 

 planting and secured 58 marked and 43 unmarked specimens of Cerion 

 viaregis and 54 marked and 105 unmarked Cerion casablancce. All the 

 unmarked specimens, which represent the first generation of Florida- 

 grown material, were at once referable to one or the other of the two 

 species; no intermediates of any kind appeared. It seems reasonable, 

 therefore, to believe that these two species do not cross. This is not 

 at all surprising when one considers the differences in the anatomical 

 structures, as pointed out in the anatomical discussion of the various 

 forms transplanted. 



