EXPERIMENTS IN THE BREEDING OF CERIONS. 5 



Another introduction was made on Loggerhead Key in 1915. This 

 consisted of 800 specimens of Cerion crassilabris ("Shuttleworth" 

 Sowerby) gathered by Dr. Mayor at Ballena Point, near Guanica Bay, 

 Porto Rico. This will be referred to later as Colony L. 



The last introduction was made in 1916, and forms Colony N on 

 Loggerhead Key. This colony consists of 8,317 specunens of Cerion 

 uvd (Linnseus) gathered by Dr. Ralph Arnold at Curagao, Netherlands 

 West Indies. 



Some of these colonies have now produced the second generation of 

 Florida-grown offspring, and it is deemed deskable to put on record a 

 complete account of the results so far attained in these breeding experi- 

 ments. We shall consider in rotation the colonies of the different 

 species from the north to the south, and give tables of measurements 

 which will show the altitude and the greater and lesser diameter of the 

 specunens. We will also give photographs of all the specimens meas- 

 ured. The njimbers given to the specimens measured will also be 

 employed in the photographs, so that the two can readily be connected. 

 It is deemed desirable to publish this large number of figures because 

 the specimens discussed could not be retained as Museum records, for 

 future observations, but had to be used for further breeding. Our 

 photographs, therefore, must take the place of the specimen itself, and 

 convey an idea of whatever variation in outline and sculpture the 

 material grown in Florida may present. 



I have selected a larger check series (100 specimens) than in my 1915 

 report, in which only 10 were used. This was deemed desirable in 

 order to show more definitely the range of variations. This check 

 series of 100 was taken at random from a large number of individuals 

 and it is beheved that it well represents all limits of variations. 



Cerions may be found on the ground, under the edges of stones, or 

 on top of them, among dead leaves or upon blades of grass, dead 

 stumps, the bases of trees, and on low bushes. They never ascend to 

 any considerable height, for we have rarely found them beyond the 

 reach of the hand above the surface of the ground. When Cerions 

 occupy an exposed position they attach themselves to the support by a 

 thin epiphragm which serves the double purpose of fixing them to the 

 support and preventing desiccation; thus sealed up they appear to be 

 able to estivate for a considerable length of time, and under such con- 

 ditions are apparently not harmed, even when exposed to the blazing 

 tropical sun for a prolonged period. 



Observations made during the years which have intervened between 

 1912 and 1919 lead me to believe that Cerions are largely nocturnal. 

 They are most active on misty nights. At such times the animals may 

 be seen on the ground, where they dig, with about one-fourth to three- 

 fourths of the animal and shell buried below the surface. Animals 



