— 
292 HELIX NEMORALIS. 
of the shell is desired to be accurately conveyed, a more exact system of 
notation is needed. M. Jules Sauveur,! sensible of the deficiencies of the 
method usually adopted, proposed that three degrees of breadth of band 
and their interspaces should be recognized ; the narrow band or interspace 
which should be less than half a millimetre in width, and indicated by a 
full point (.): a broad band or interspace, which should exceed 13 mill. 
in width, and be indicated by a horizontal line (—); and a median band 
or interspace which should range from half a millimetre to 14 millimetres 
lites Bie! Fic. 355. Fic. 356. Fic. 357. 
Helix nemoralis L., showing the greater precision of the Sauveurian method in 
indicating the character of the banding. 
Fic. 354.—Shell with five bands and indicated by the formula j= 3s, 
Fic. 355.—Shell bearing the same bands, but the increased breadth indicated by 1.2.3.4.5. 
Fic. 356.—Shell with four bands, formulated as 0 Paty y= Bye 
Fic. 357.—Shell bearing the same bands, and indicated by the formula 0 2—(34)—5. 
in breadth, and be represented by a comma (,). By the use of these three 
additional signs, practically all the band variations and their peculiarities 
may be precisely recorded, and as it is calculated that — without allowing 
for the supernumerary or interrupted banded forms—there may be 17,656 
modifications of the banding in specimens with from one to five bands, 
these slight modifications of the usual formula would appear to be desirable. 
Dr. Boycott and Rey. E. W. W. Bowell have also proposed a method of 
indicating the relative importance of each band ; they agree with Sauveur 
that three grades of strength should be recognized : full, half, aud quarter 
strengths. If, for example, the third band be of full strength or more—and 
in estimating the relative strength, a deeply pigmented narrow band is con- 
sidered to be equivalent to a broader and paler one—they propose it shall 
be indicated by the ordinary numeral 3 in the usual way; if the band be 
half strength only, it would be shown by the fraction 3, the denominator 
being the numeral denoting the position of the band, the numerator being 
the numeral 2 to typify the half strength of band; similarly a band of 
quarter strength would be represented by $. 
Rey. E. Adrian Woodruffe-Peacock has detected a certain degree of 
correlation or relationship between the various bands, observing that when 
the second band is absent, the fourth band is also absent or greatly 
reduced; and if the third band be less than normal width, the fifth is 
usually diminished on the basal side. He has also devised an ingenious 
method of registering the relative dimensions of each band and each 
interspace.” He conceives the entire space occupied normally by the five 
bands to be divided into twenty-four equal spaces, and apportions these 
out according to the various widths of the bands and spaces in each 
individual, the numeral used not representing the position of the band or 
interspace, but the number of such spaces it occupies. On this system, 
the typical five-banded shell would be expressed by the formula 122231433, 
the large figures representing the relative breadth of the bands and the 
smaller figures the widths of the interspaces. 
1 Annales Soc. Mal. Belg., ii., pp. 59-108. 2 Naturalist, 1909, pp. 171-174 and 257-259. 
