916 THE AMERICAN NATURALIST.  [Votw. XXXII. 
to all shells whose ground color is fawn, and the formula of 
each is added. Not only in formula, but also in color do the 
shells intergrade, and the personal equation in nomenclature is 
large. This, however, affects the deductions from large series 
but little. Great variation also appears in the width of the 
bands and to some extent in their color, but these distinctions 
have not been noted in this paper. 
TABLE II.— FREQUENCY OF VARIETIES OCCURRING MORE 
THAN TWENTY TIMES. 
(In percentage.) 
A. B. C D. A. B. C: D. 
12345 ge grt 316 47. | 12045; Ho 1.2 = 39 
123 (45) 124 10s DM2 401 045 LI I.I 2.2 2. 
(12) 3 (45) 4. 4.4 5:2 0.2 | 12345 0.6 0.5 2.9 1.3 
12345 1.2 0.9 3.1 00300 8.2 88 0.2 0.7 
10345 6. 6.5 2.5 6.6 | 00000 © 4- 2.6 5: 4.6 
12345 36 4 37 59 
“s D” isa series of 151 shells, sent by Mrs. Brooke to Pro- 
fessor Cockerell, and described in Sczence.1_ While not large, 
it shows the same general tendency as the other series, resem- 
bling “4” and “B” much more closely than “C.” It is curi- 
ous, however, that the series contained but one 00300, as this 
formula is frequent in Mrs. Brooke’s garden. This series 
resembles “A” and “B?” also in containing quite a number 
(4.6%) of other varieties than 4de//ula. 
In summing up Table II, we find that these eleven varieties 
comprise 82.3% of all the shells in series “A,” and 82.4% of 
those in “B,” but only 75.7% of those in “C.” They also 
comprise 86.8% of “ D.” The great scattering of the variation 
is thus shown by the fact that in “ Æ” 17.7% of the series con- 
tain 102 varieties; in “B” 17.6% contain 102 varieties, while 
in “C” 24.3% contain 127 varieties. 
These series may be looked at from a somewhat different 
standpoint, as shown by the following table, in which the vari- 
eties are classified. Here the variation of a band may mean 
that it becomes rudimentary, disappears, or splits. It is doubt- 
1 Science, loc. cit. 
