Report on the Bahama Cerions planted on the Florida Keys. 



211 



The 20 specimens of the first generation from the north colony of 

 Loggerhead Key, Tortugas (plate 2, top and bottom rows), are extremely 

 interesting. They possess a greater number of whorls than the check 

 series or parent generation (plate 2, middle row). The altitude is also 

 greater, the average of the check series being 26.37 mm.; that of the 

 present generation, 28.80 mm. The variation in this measurement is 

 also much increased, ranging from 25 mm. to 34 mm., as against 24.5 

 mm. to 28.5 mm. of the check series i. e., there is a range of 9 mm. 

 in the present series against 4 mm. of the check series. This raises 



TABLE 3. First generation of the "White House Type" cerions from the 

 north colony of Loggerhead Key, Tortugas, Florida. 



[Plate 2, top and bottom rows.] 



*Altitude estimated; shell not quite adult. 



the variation in altitude 7 mm. above that observed in the first gen- 

 eration born and grown upon Bahia Honda, Florida. The average 

 diameter in the north colony drops below that of the check series, 

 being only 12.28 mm., against 12.59 mm. The range of variation, 

 however, is much greater i. e., 11 mm. to 14.5 mm. against 12 mm. 

 to 13.3 mm. of the check series; or 3.5 mm. against 1.3 mm. This 

 variation exceeds even that of the Bahia Honda grown first generation, 

 in which it was 2.3 mm. 



The shape, coloration, and sculpture have also undergone decided 

 modification in some of the specimens. There is a pronounced tendency 

 in the entire lot toward greater elongation. This tendency reached its 



