886 H. H. NEWMAN AND J. THOMAS PATTERSON 
We have studied this shell in considerable detail and have 
compiled the data secured in table 12. Here it will be noted 
that 391 of the 625 scutes have but three hairs each, and further- 
more that there is a strong tendency for the 3’s to be distributed 
on the lateral parts of the shield. However, the most striking 
fact revealed in the table is indicated in the fourth column, where 
the total number of hairs for each band is given. Bands 2 and 8, 
which show the extremes in scute variation, have exactly the same 
number of hairs, while the two extremes in hair variation, bands 
7 and 9, are but six hairs apart in their totals. 
TABLE 12 
Shell 2, with 625 scutes showing distribution of 3-hair and 4-hair scutes 
DISTRIBUTION OF 3’5 AND 4’S IN BANDS | LATERAL DISTRIBUTION OF 3’ 
BANDS 
3-Hair Type | 4-Hair Type | Number of | ‘Left | Middle Right 
ee = —— | a 
| 
lense Ae ae 49 | 22 | 235 | 19 16 14 
Din aS Tee 34 | 33 | oA | la 12 8 
Sy ie 37 | 31 | 225 Pas 5 14 
A | 38 | 30 | ode) Ul Teac Bias 14 
aks 38 30 | DOA Wy 19's Volt ee 13 
Be 49 op Dare Tala Ooh Sail) grat 22 
7 SR u SU ion bd 41 27 Fe os 7 16 
Be ea 58 15 23 +08) JO1e Veet 21 
Dia tae a ral 47 7 Oe ee mate er eh: 16 
otal 20a. alee | 2109 | 176 77 
| 138 
The question naturally arises: Can the high number of scutes 
exhibited by this specimen be accounted for by the fact that so 
many of them are of the three-hair type? Undoubtedly it can, 
but the affirmative answer necessitates the assumption that the 
integumentary primordium out of which each band arises contains 
a definite number of hair follicles, which are later distributed 
into groups of 3’s and 4’s according to the propensities of the 
formative scutes. Itis evident upon this assumption that a ten- 
dency for the scutes toform about groupsof four hairs would result 
in the production of a shell having a low number of scutes, while 
