In the historic period, it would seem, no sharp line was drawn, or felt to exist, between the various types of 'insulae'.

In the main, the square or squarish-oblong was preferred.
Local accidents, such as the convenience of the site at Carthage, led to occasional adoption of the narrower oblong.
The Roman land-surveyors, it is true, distinguished the square and the oblong in a very definite way.

The square, they alleged, was proper to the Italian land or to such provincial soil as enjoyed the privilege of being taxed--or freed from taxation--on the Italian scale.

The oblong they connected with the ordinary tax-paying soil of the provinces.

This distinction, however, was not carried out even in the agrarian surveys with which these writers were especially concerned,[63] and it applies still less to the towns.