linear scale upon the inôÙstruôÙment, the relôÙaôÙtive breadths of the conôÙsecôÙuôÙtive whorls, and that of the terôÙminal chamôÙber to the rest of the shell, might also, though someôÙwhat roughly, be deôÙterôÙmined. For instance, in Terebra dimidiata, the apical angle was found to be 13ô¯, the sutural angle 109ô¯, and so forth.
It was at once obvious that, in such a shell as is repôÙreôÙsentôÙed in Fig. 267 the enôÙtire outôÙline of the shell (always exôÙceptôÙing that of the imôÙmediate neighôÙbourôÙhood of {530} the mouth) could be restored from a broken fragment. For if we draw our tangents to the cone, it follows from the symôÙmetry of the figure that we can conôÙtinôÙue the proôÙjecôÙtion of the sutural line, and so mark off the sucôÙcesôÙsive whorls, by simply drawing a series of conôÙsecôÙuôÙtive parallels, and by then filling into the quadôÙriôÙlatôÙerals so marked off a series of curves similar to one another, and to the whorls which