210 Papers from the Department of Marine Biology. 
THE “WHITE HOUSE TYPE.” 
In order to determine the amount of variation which has taken place 
in the first generation of these snails born and matured in Florida, a 
check series (plate 1, upper row, and plate 2, middle row) of 10 speci- 
mens was selected from a lot of more than 1,000 from Andros Island, 
Bahamas. These were collected at the same time and place in which 
the specimens planted on the Florida Keys in 1912 were obtained. 
These 10 specimens are part of a handful which was taken at random 
from the box containing the lot, and the 10 specimens in turn were 
picked from this handful without looking at them. We therefore 
assume that they represent a fairly typical average series. They are 
characterized by quite uniform outline and sculpture. 
These 10 specimens from left to right yield the data shown in table 1. 
TaBLeE 1.—Check series “White House TABLE 2.—First generation of ‘‘White House 
Type’’ cerions. Type” cerions from Bahia Honda Key. 
Measurement Measurement 
{Roe of shell. of shell. 
ioe men ae | Pian *| Alti- 
tude. | eter.* tude. 
mm. mm. mm. 
1 10.3 25.5: | 13.3 So 
2 LOZ 27 23 32.8 
3 10.4 26.54) 1253 29 
4 10.8 28-5) || L203 ; 29.8 
5 10.1 ae 5a} 1S : 33 
6 10.3 26.3 | 12 : 31 
7 10.5 27, 13 30. 
8 9.6 25.4 | 1322 : 2D: 
9 10.1 AT em me PEO) : 24. 
10 10.3 27 12.3 29. 
ANVELAGE. =... 10.25 | 26.37| 12.59 Average...... ; 29. 
Greatest...... 10.8 | 28.5 | 13.3 Greatest...... 32.8 | 14:4 
MCast)«, <..co-s <x. 9.5 24.5: | 12 TG CASE s ica sve sions 2 2A 5 ad 
*This measurement in each case is the tLength estimated. 
diameter of the shell from just back of tShell not quite adult. 
the lip to a point diametrically opposite. 
A comparison of these first Florida generation shells (plate 1, lower 
row) with the check (Bahama parent generation) series (plate 1, upper 
row) shows that the general outline and sculpture seem to have been 
maintained, but the texture of the shells has a more glossy and harder 
appearance. The measurements show an increase in the number of 
whorls—a greater altitude with a greater range of variation. In the 
check series the total variation was 4mm. In the Florida-born off- 
spring it is8.3mm. The diameter has also increased materially, and 
with it the range of variation. In the check series this is 1.3 mm.; 
in the above, 2.3mm. Wemay, therefore, say that the first generation 
from Bahia Honda, Florida, represents a much more variable organism 
than the parent stock in the Bahamas. 
