EXPERIMENTS IN THE BREEDING OF CERIONS. 



45 



In altitude our Florida-grown material varies from 34.4 mm. to 22.3 

 mm. as against 32.9 mm. to 24 mm. in the check series. In diameter 

 our Florida-grown specimens vary from 15 mm. to 10 mm., while in the 

 check series the variation is from 15.6 mm. to 11 mm. These measure- 

 ments, however, it should be remembered, cover 4,463 specimens and 

 were we to examine a check series of equal size it is not at all improbable 

 that these slight differences would also be present. In other words, 

 the measurable characters show no decided change over anything that 

 one might find in the Bahama material. 



Of the second generation of Florida-grown specimens we have so far 

 obtained only 102 specimens. These, like the first generation, show a 

 little wider range of variation in measurements, but no differences in 

 shell characters. The range of variation here is 12.1 to 9.7 whorls, 

 while in the check series it is 12.1 to 10. In altitude the second gener- 

 ation varies from 31.3 mm. to 23.2 mm. against 32.9 mm. and 24 mm. 

 of the check series. In greater diameter the variation is 15 mm. to 

 10.1 mm. against 15.6 mm. and 11 mm. We may therefore say that 

 the summary remarks applying to the first generation also obtain here. 

 Table 28 gives a little more detailed account of this generation. 



TABLE No. 28. Second generation Florida-grown Cerion casablancce. 



CERION CRASSILABRIS ("SHUTTLEWORTH" SOWERBY). 

 THE LOGGERHEAD KEY COLONY L. 



In May 1915 Dr. Mayor collected a lot of specimens of Cerion crassi- 

 Idbris, at Balena Point, near Guanico Bay, Porto Rico, 800 of which we 



